Sudanuniversity of Science & Technology

بسم الله الرحمن الرحيم

SudanUniversity of Science & Technology

College of Veterinary Medicine

Department of Veterinary Medicine & Animal Surgery

Theriogenology I (Reproduction & GynaecologyI)

4th year

Course Contents

1-Anatomy of Female Reproduction.

2-Physiology of Female Reproduction (hormonal control).

3-The Puberty and Sexual Maturity (reproductive cycle).

4-The Fertilisation and Development of the Conceptus (time of fertilisation in different animals).

5-The Pregnancy (stages and types of placenta).

6-Methods of Pregnancy Diagnosis

7-Abnormalities and Teratogens.

8-Parturition and the Care of Parturient animals.

9-The Puerperium and the care of the Newborn.

10-Reproduction in the Camel.

Anatomy of Female Reproduction

The genitaltract of non-pregnant cows normally lies in the pelvic cavity and consists of the vulva, vagina, cervix, uterus, Fallopian tubes (oviducts), ovaries and their supporting structure. Most of the reproductive structures can be palpated through the rectum. The reproductive tract is supplied by blood from the utero-ovarian arteries of which the middle uterine artery is the largest. The autonomic nerves are supply ovary; uterus and oviducts, while pudic nerve supplies vagina, vulva and clitoris.

The uterus of cowis a muscular organ (V-shaped) consisting of a body, about 4-5 cm long, and two uterine horns (cornua), each 35-40 cm in length and 1-3 cm in diameter. The uterus is suspended by the broad ligament (mesometrium) in a coiled or curled manner. The attachment of the broad ligament is dorsolateral in the region of the illium, so that the uterus is arranged like ram’s horns (convexity dorsal). Its size varies with breed, age, parity, pregnancy and disease.

The cervix is a sphincter-like structure with a thick wall and a narrow lumen. This lumen is tightly closed, except during oestrus and at parturition, and the cervix forms a barrier between the uterus and the outside environment. The length of the cervix varies from 1.5 cm in heifers to 8 cm in multiparous cows of larger breeds.

The mare’s uterus is T-shaped with 2 short uterine horns and a body. The uterine horns extend upward toward the ovaries. The uterine body is palpated via rectum approximately 45-50 cm into the rectum. The uterus will curve up toward the ovaries, thus allowing you to differentiate it from the small colon. There is a cylindrical structure and is about 5-8 cm long.

The female dog (bitch) has a bicornuate (Y- shaped) (or two-horned) uterus which ends as the cervix, a short canal which connects to the vagina. The cervix is muscular with fibrous tissue support. The surface of the uterus in the queen cat is usually smooth and regular (unlike the dog). When pregnant, bulges occur at regular intervals.

Function of uterus:

Endometrium and its fluid play a major role in the reproductive process:

1-Sperm transport from the site of ejaculation to the site of fertilisation in the oviduct.

2-Regulation of the function of the corpus luteum (CL).

3-Initiation of implantation, pregnancy and parturition.

The vagina of cow extends backwards from the cervix and opens into the vulva. Its length varies with breed and stage of pregnancy. The vaginal epithelial cells near the cervix secrete mucus, especially around the time of oestrous.

Bitches often have a vaginal stricture, which is a remnant of where the vagina and vestibule fused together during embryonic development. This stricture is often asymptomatic and is broken down during mating.

The vestibule extends from vagino-vestibular junction cranially to vulval lips caudally (8-12 cm length in the cow, mare and camel; 2-3 cm in the ewe and goat, and 2 cm in the cat). It acts as the point of attachment for the entire genital tract to contact upon when expelling the fetus at term. In the bitch, the vestibule makes a steep downward turn exits within the vulva.

The clitoris is located at the ventral commissure of the labia and it is well developed in the mare.

The ovaries of cow are oval-shaped (almond) structures 1-4 cm long and 1-3 cm in diameter; their size depends on the stage of the reproductive cycle. They are located on the cranial border of the broad ligaments, just lateral to the uterine horns(the size of mature follicle 1-2cm, CL 3.5cm).The ovary of a new-born heifer may contain up to 150.000 primordial follicles. However, only a few of these mature and release an ovum.

The ovaries of the female camel(flattened oval with grooves)are located on the cranial border of the broad ligaments, just lateral to the uterine horns. Both ovaries are enclosed within the ovarian bursae (the size of mature follicle 1-2.2 cm, CL 1.2-3.7 cm).

The ovaries of the mare(kidney or bean-shaped) are suspended in the sublumber region (the size of mature follicle up to 9 cm, CL 2-3 cm)..

The ovary of the queen catis suspended from the dorsal abdominal wall by the mesovarium within which is a plexus of blood vessels and which has an outer covering of smooth muscle.

The predominant tissue of the ovary is the cortex (ovary composed of the medulla and cortex). The ovary is supported by the meso-ovaruim ligament (The ovary is supported dorso-laterally by the broad ligament, and medially by the proper ligament.).The ovary has two major functions: gametogenesis (the production of female gamates) and steriodogenesis (the production of steroid hormones. which play vital roles in the reproductive cycle.

The ovaries are linked to the uterus by the Fallopian tubes which open anteriorly into fimbriae-funnel-shaped structures closed to, but not attached to the ovaries. The parts of the oviduct are the isthmus, ampulla, and, the infundibulum with its fimbriae.

The isthmus is the constricted portion lying next to the uterus. It is continues directly into the uterine horn at the uterotubal junction. In the mare the isthmus opens into the uterine lumen through a small slit on a mound or papilla. In the cow and ewe there is marked flexure at the transition of the isthmus with the elongated curving end of the uterine horn. The latter has a very narrow lumen.

The ampulla widens into a funnel shaped part called the infundibulum. In the queen cat the infundibulum is over the surface of the ovary but does not surround the ovary as in the dog. The opening of the oviduct into the abdominal cavity is called the ostium abdominale, which is surrounded by a fringe of irregular processes called fimbriae, which form the cranial extremity of the tube.

The paired Fallopian tubes are the means by which ova, released from the ovaries at ovulation, reach the uterus. The fimbriae guide unfertilized eggs from the ovary into the Fallopian tubes. The length of oviduct about 25 cm in the cow (30 cm in mare) and is suspended by meso-salpinx ligament (part of broad ligament).

Anatomy and physiologyof female reproductive system in the chickens:

The female reproductive system of the chicken is divided into two separate parts: the ovary and the oviduct.In almost all species of birds, including chickens, only the left ovary and oviduct are functional. Although the embryo as two ovaries and oviducts, only the left pair develops. The right typically regresses during development and is non-functional in the adult bird.

The ovary is a cluster of developing yolks or ovaand is located midway between the neck and the tail of the bird, attached to the back.The ovary is fully formed when pulletchicks hatch, but is very small until they reach sexual maturity.

Each ovum starts out as a single cell surrounded by a vitellinemembrane. As the ovum develops, yolk is added. The color of the yolk comes from fatsoluble pigments called xanthophylls contained in the hen’s diet.The ovum, which is enclosed in a sac, ruptures along the suture line or stigma.

Occasionally the vitelline membrane is damaged and pale spots or blotches develop on the yolk. This is referred to as mottling. Although the appearance of the yolk is changed, there is no affect on the egg’s nutritional value or flavor.

The female’s reproductive system is sensitive to light exposure, especially the number of hours of light in a day. The release of the next ova typically occurs 30-75 minutes after the previous egg has been laid. If the egg was laid too late in the day the next ovulation will wait till the next day and the hen will have a day when she doesn’t lay an egg.

The second major part of the female chicken’s reproductive system is the oviduct. Theoviduct is a long convoluted tube (25-27 inches long when fully developed) which isdivided into five major sections. They are the infundibulum or funnel, magnum, isthmus,shell gland (uterus), and vagina.

The first part of the oviduct, the infundibulum or funnel, is 3-4 inches long, and engulfsthe ovum released from the ovary.The ovum or yolk remains in the infundibulum for 15-18 minutes.Fertilization, if it is going to occur, takes place in the infundibulum. Theinfundibulum also serves as a reservoir for spermatozoa so that fertilization can takeplace.

The next section of the oviduct is the magnum which is 13 inches long and is the largestsection of the oviduct as its name implies. Theovum or yolk remains here 3 hours during which time the thick white or albumenisadded.

The third section of the oviduct is the isthmus which is 4 inches long. The developingegg remains here for 75 minutes.The isthmus is where the inner and outer shell membranes are added.

The next section of the oviduct is the shell gland or uterus. The shell gland is 4 -5inches long, and the ‘egg’ remains here for 20 plus hours.As its name implies, theshellis placed on the egg here. The shell is largely made up of calcium carbonate.The hen mobilizes 47% of her body calcium from her bones to make the egg shell, withthe diet providing the remainder of the required calcium. Pigment deposition is alsodone in the shell gland.

The last part of the oviduct is the vagina which is about 4-5 inches long and does notreally play a part in egg formation. The vagina is made of muscle which helps push theegg out of the hen’s body. The bloom or cuticle is also added to the egg in the vaginaprior to oviposition (the laying of the fully formed egg).

Near the junction of the vagina and the shell gland, there are deep glands known assperm host glands. They get their name from that fact that they can store sperm forlong periods of time (10 days to 2 weeks). When an egg is laid, some of these spermcan be squeezed out of the glands into the oviduct so that they can migrate farther upthe oviduct to fertilize an egg. This is one of the really remarkable things about birds;the sperm remain viable at body temperature.

In chicken hens, ovulation usually occurs in the morning and under normal daylightconditions, almost never after 3:00 PM. The total time to form a new egg is about 25-26 hours. This includes about 3½ hours to make the albumen, 1½ hours for the shellmembranes, and about 20 hours for the shell itself.

Birds lay eggs in clutches. A clutch consists of one or more eggs laid each day, followedby a rest period of about a day or more. Then another egg or set of eggs is laid.

Endocrinology of Female Reproduction

Embryology:-

The fetal reproductive system consists of two sexually non differentiated gonads, two pairs of ducts, urogenital sinus and vestibular folds.

The system arises primarily from germinal ridges on the dorsal side of abdominal cavity (male or female) (embryonic bisexuality).

Wolffian and Mullerian ducts are both present in the sexually undifferentiated embryo. In the female, the Mullerian ducts develop and the Wolffian ducts atrophy. The opposite is true in male.

The female Mullerian ducts fuse caudally to form a uterus, a cervix and anterior part of a vagina. Urogenital sinus gives rise to the vestibule (lips of vulva).

The Reproductive Hormones:-

Reproductive hormones are derived primarily from 4 majors systems:

Various areas of the hypothalamus.

Anterior and posterior lobes of the pituitary gland.

Gonads: testes and ovary including their interstitial tissues and CL.

Uterus and placenta.

The hormones of reproductive are also classified into two groups, according to their mode of action

1-Primary hormones: regulate the various reproductive processes (ovulation, sexual behavior, fertilisation, implantation, maintenance of gestation, parturition and lactation) (table 1).

2-Metabolic (secondary) hormones: which indirectly influence of reproduction (general well being, metabolic state and growth of the animal) (table 2).

Table (1): Primary Hormones of Reproduction

Source or gland / Releasing hormones / Physiological functions
Hypothalamus / Gonadotropin-releasing hormone (Gn-RH).
Growth-hormone-releasing hormone (GH-RH).
Thyrotropin-releasing hormone (TRH).
Prolactin-inhibting factor
(PIF).
Corticotropin-releasing hormone (CRH). / Stimulates release of FSH and LH.
Stimulates release of growth hormone.
Stimulates release of thyroid stimulating hormone (TSH) and prolactin.
Inhibits release of prolactin.
Stimulates release of ACTH.
Anterior pituitary / Follicle-stimulating hormone (FSH).
Luteinizing hormone (LH).
Prolactin (PRL). / Stimulates follicular growth, spermatogenesis, oestrogen secretion.
Stimulates ovulation, corpus luteum function: stimulates secretion of progesterone.
Promotes lactation, stimulat-
es CL function and progesterone secretion in some species, promotes maternal behavior, promotes tissue and bone growth.
Posterior pituitary / Oxytocin (also produced in ovary). / Stimulates uterine contract-
ion, parturition and sperm and egg transport. Facilitate milk ejection. Possible luteolytic function.
Placenta / Human chorionic gonad-
otropin (hCG).
Pregnant mare serum gonadotropin (PMSG). / LH activity.
Maintians CL of pregnancy in primates.
FSH activity.
Stimulates formation of accessory corpora lutea in mare.
Ovary / Oestrogens.
Progestins (Progesterones) / Promotes sexual behavior; stimulates secondary sex characteristics, growth of reproductive tract, uterine contractions and mammary duct growth.
Controls gonadotropin release, stimulates Ca uptake in bones.
Acts synergistically with oestrogen in promoting oestrus behavior and preparing reproductive tract for implantation.
Maintains pregnancy.
Uterus / Relaxin.
Prostaglandins / Dilates cervix.
Causes uterine contractions and is luteolytic.

Table (2): Secondary Hormones of Reproduction

Source or gland / Releasing hormones / Physiological functions
Placenta / Oestrogen.
Progesterone. / See ovary (table 1).
See ovary (table1).
Anterior pituitary / Somatotropin hormone (STH).
Thyroid-stimulating hormone (TSH).
Adrenocorticotropic hormone (ACTH). / Body growth; protein synthesis.
Stimulates thyroid gland.
Thyroxine release and iodine uptake by thyroid.
Stimulates adrenal cortex.
Release of adrenal corticoids.
aedPosterior pituitary / Antiduiretic hormone (ADH). / Water balance.
Thyroid / Thyroxine. / Body growth; development and maturation; oxidation of feeds.
Parathyroid / Parathormone. / Calcium and phosphorus metabolism.
Adrenal cortex / Aldosterone.
Cortisol & Cortisone. / Electrolyte and water metabolism.
Carbohydrate, protein, and fat metabolism.
Pancreas. / Insulin / Carbohydrate, protein, and fat metabolism.

Feedback Mechanism:

The synthesis, storage and release of hypothalamic hormones are regulated by both pituitary and steroid hormones through two feedback mechanisms, along and short loop. Long feedback involves interaction among gonads, pituitary and hypothalamus. In the short feedback system, the level of pituitary gonadotropin can influence the secretary activity of releasing the gonads. Depending on their concentration in the blood, steroid hormones may exert a stimulatory (positive) or inhibitory (negative) feedback. Positive feedback results when an oestrogen or progesterone stimulates the release of gonadotropin, such as LH. Negative feedback results when large levels of progesterone prevent the releasing of gonadotropin.

Reproductive cycle

Relates to various phenomena:-

Puberty and sexual maturity, the breeding season, the oestrous cycle, postpartum, sexual activity, and aging. These components are regulated by environmental, genetic, physiological, hormonal, behavioral and psychosocial factors. The level of fertility initiated at the time of puberty is maintained for a few years before it begins to gradually decline due to aging. Secretion of (Gn-RH), LH and FSH always begins during fetal life. In the cow and ewe it starts early, shortly after sex differentiation (2 months of pregnancy) (sow 1.5 months). This secretion is slightly reduced 2 months before births in cattle, near term in sheep and 1month after birth in pigs (related to maturation of central nervous system).Gonadotropin levels remain low up to the onset of puberty.

Sexual Development (activity):-

• Weaning life.
• Prepubertal life.
• The puberty.
• Sexual maturity.

The Puberty:

Is a period of sexual activity. The age when first oestrous accompanied by spontaneous ovulation occur. The female becomes sexually mature and able to reproduce.

During the prepubertal period the growth of the genital organs is very similar to that of the other organ system, but at puberty their growth rate is accelerated.

The age of puberty in females of domestic species:

• Mare: 1-2 years.
• Cow: 7-18 months in foreign breeds and 2-3 years in local breeds.
• Ewe: 6-15 months.
• Doe or nanny goat: 4-8 months.
• Sow: 6-8 months.
• Bitch: 6-20 months.
• Queen cat: 7-12 months.
• Female camel: 2-5 years.

External factors influencing the time of onset of puberty:

1-Nutrition:Animals that are well fed with good growth rates reach puberty before those they are poorly fed with slow growth rates.

2-Season of the year:Seasonal breeder such as the ewe, mare and queen cat.

3-Proximity of the male:Studies in sheep and pigs have shown the at exposure to the male of the species will advanced the timing of the onset of puberty (ram or boar effect).

4-Climate.

5-Disease: Influence on the growth rate.

6-Stress: Loss of weight influence adrenal gland activity