Physiology of Pregnancy PDF

Physiology of Pregnancy Presented by Dr/ Mohamed Wagdy Rezk Mansour Lecturer of Theriogenology Theriogenology department Faculty of veterinary medicine University of Sadat City [email protected] Gestation Period or Pregnancy Duration Period o...

Physiology of Pregnancy Presented by Dr/ Mohamed Wagdy Rezk Mansour Lecturer of Theriogenology Theriogenology department Faculty of veterinary medicine University of Sadat City [email protected] Gestation Period or Pregnancy Duration Period of time from fertilization to parturition or from conception till birth Factors affecting the length of gestation period I. Hereditary II.Environmental III.Fetal IV.Maternal factors factors factors factors  I. Hereditary factors 1.Species 2. Breed 3. Fetal genotype Monotocus animal Beef cattle longer In hybrids ( horse X donkey) (cow and mare) than dairy cows gestation period close to paternal have gestation than to maternal. period longer than Mare X stallion Foal (320-360)days polytocus animal Mare X donkey Mule (360-380)days (sheep and goats) Animal Pregnancy (month) Pregnancy (days) Cow 9 280±15 Buffalo 10 310±15 Sheep & goat 5 150±15 Mare 11 330±15 donkeys 12 365±15 camel 13 390±15 bitch 2 63 (58-67) Cat 2 59 (58-65) sow 114 Elephant 21-22 645 Giraffe 14-15 430 Bear 7-8 230 Kangaroo 1-1.5 42 Zebra 12-13 375 Monkey 164 Deer 201 Lion& Tiger 108  II.Environmental factors 1. Feeding 2. Season Gestation period in well fed Foeti born in summer or autumn animals shorter than ill-fed animals have a shorter gestation period by 3 days than those born in winter or spring  III.Fetal factors 1. Litter size 2. Number of foeti 3. Sex of Fetus Inverse relationship Male foeti have a Twin in monotocus animals (cow between gestation longer gestation and buffaloes) have shorter period and litter size period than female gestation period than single fetus in polytocus animals foeti  IV.Maternal factors Number of previous parturitions Primiparous animals has shorter gestation period than pluriparous  Gestation Period 1. Germinal period Start from fertilization and ends by (Ovum stage) implantation of blastocyst in the endometrium Start after implantation and during which 2. Embryonic stage the embryo and placenta are formed (organogenesis) 3. Fetal stage Start with organogenesis and ends by parturition  1. Germinal period (Ovum stage) Start from fertilization and ends by implantation of blastocyst in the endometrium -The fertilized ovum reach uterus 3-5 days (morula stage 16-32 cell stage). - At 10-12 days, the blastocyst begin to be attached to the endometrium.  Mechanism of implantation - Continuous growth of blastocyst leads to fragmentation of zona pellucida. - The trophoblast cells forming finger like processes (Chorionic villi) invade the endometrial mucosa. Period takes up to:- 7th days in bitches 10th days in ewes 12-13th days in cows and buffaloes 14th days in sows 29th days in mares  2. Embryonic stage Start after implantation and during which the embryo and placenta are formed (organogenesis). - Body becomes well differentiated. - The heart prominence appear at the end of 4th week. - Anterior and posterior 2 buds give rise to fore and hind limbs appear at the end of 5th week. - Formation of fetal membranes. - From 13th to 45th days in cows - 13th to 50th days in buffaloes - 29th to 55th days in mares - 10th to 35th days in sheep and goats  Formation of fetal membranes - Fetal membranes surrounding the developing embryo. - The blastocyst composed of inner cell mass Fetal tissue and outer trophoblast Fetal membranes (amnion, chorion, allantois). 1. Amnion - Membrane formed 2 weeks after conception(18th day in cattle). - Arise from the sides of embryo as double walled sac that surrounding completely the developing embryo except at the umbilical ring. - The amnion or water bag filled with clear viscous fluid and contain carbohydrates, proteins, fat and minerals. - The buccal cavity and urethra of the fetus opens in the amniotic cavity. Amniotic plagues - Small (0.5 – 1.5 cm) irregular shaped white elevated epithelial thickening on which calcium ions may be deposited. - Formed in 3rd month on inner surface of amniotic sac and separated and became keratinized at 7th month of gestation. Functions of the amnion:- 1. Forms a protective cushion against external shock or pressure of adjacent tissue organs. 2. Prevents adhesions between the surface of the embryo and the surrounding structures. 3. At parturition, the amnion act as a wedge to dilate the cervix and after its rupturing the escaped viscous fluid lubricates the soft birth canal of mother animal. Fetus and placenta (amniotic surface Placenta, umbilicus, and fetal aspect of amnion. exposed). The umbilicus and amnion Numerous coalescing amniotic plaques cover are covered by amniotic plaques. the amnion.  2. Allantois - Completely formed from 24 – 28 days after conception. - Arises as an out pocketing of the hindgut. - Connected to the fetal bladder by the urachus which runs through the umbilical cord. Allantoic calculi (hippomanes) Dark fleshy mass of cellular debris, fat and degenerated blood vessels (cow, sow, ewe, bitch and mare (foal bread). Functions of the allantois:- 1. With amnion, form a hydraulic pressure which help cervical dilatation during parturition. 2. Act as a reservoir for the waste products of the fetus. 3. Forms a connection between fetal and maternal circulation.  3. Chorion - Outer fetal membrane surround embryo, amnion, allantois direct apposition to the uterine endometrium. - In mare, there is a bare area on the part of chorion facing the internal os called (cervical star).  Item Amniotic fluid Allantoic fluid Colour & Clear amber yellow Dark yellow (brownish) appearance Consistency viscous watery Its secretion Mainly by amniotic urachus membrane Composition Glycogen, fat, proteins, Nearly the same + urine inorganic salt and element Functions Bactericidal effect and Amorphous, semisolid, prevent adhesion fetus rubber like irregular mass (Hippomanus or foal bread) source nourishment fetus Volume Cow and buffalo 3-5 L 4-15 L Mare 3-7 L 4-10 L Sheep and goat 0.4-1.2 L 0.2-1.5 L Bitch 10-30 cc 10-50 cc Cat 10-30 cc 3-15 cc -The allantoic sac (one fifth is left uncovered) so the allanto-amnion in this part bare not covered by the allanto-chorion, thus the amniotic sac may burst 1st during parturition followed by the allantoic sac (10%). - In mare the allanto-chorion cover completely the allanto-amnion. The allantoic sac burst 1st during parturition (100%).  3. Fetal stage (period) - Start with the organogenesis and ends by parturition. - From 45th days in cows - 50th days in buffaloes - 55th days in mares - 35th days in sheep and goats to full term - The fetus grows in size as a result of the growth and differentiation of its different organ Changes occurring during fetal stage A. Growth changes 1. The increase in length (Crown Rump), (Curved Crown Rump) Cow Calf: grows at a rate of 1 cm/ week until 11th week then 2cm/ week afterwards. - The length of the fetus (CR) - Crown (C) point between the 2 eyes - Rump (R) root of the tail - CR= month of pregnancy X (month of pregnancy + 2) Buffalo calf: The age of the fetus is determined from the curved vertebral rump(CVR) Foal: The length increases at a rate of ( 1 cm / week during the 1st weeks, then 2.5 cm / week till full term. CR= month of pregnancy X (month of pregnancy + 1). (Crown Rump length ) CRL 2. Hairing Month of pregnancy calf Foal 4th Lips and eye lids lips 5th Forehead and Eye lashes and dorsal extremity tip of tail 6th mane 7th tip of tail tail 8th back back 8.5-10th Whole body Whole body  B. Maturation changes The maturation of fetus was a sign of normal gestation period. The whole body must be covered with hair without any area of alopecia except inner of thigh. Signs of maturity (ripeness) in newly born animals 1. Weight 2. Length (CR) and (CVR) 3. Hairing (distribution, color, length) 4. Teeth (regularity, eruption) Items Calf Foal Lamb & Kids Puppies & Kittens Weight 25-45 kg cow calf 30-60 kg 1.5-3.5 kg (breed and 0.25-0.5 kg (varies 25-50 kg buffalo calf number of given feti) greatly in different (depending on age breeds of dogs and and breed) cats). Length 70-75 cm (age and 100-150 cm (age and 30-40 cm Varies greatly breed) breed) Hairing 2 cm length all over Hair short irregular Well developed and Covered with thick body and thick hair around thick hair around and short hair. 4 cm around mane. navel umbilicus No hair around navel Teeth Well developed and 2 centrals erupting Tips of cutting teeth No teeth erupting regularly arranged 4 fro the gum in both penetrating gum from the gum milky teeth in the jaws lower jaw N.B) The eye lids of newly born dogs and cats closed with an epithelial coverings for 8-10 days with a consequent temporary blindness. Importance of judging maturity of fetus 1. Pay more attention to immature animals (good feeding and keeping). 2. To take care of the farm in cases of premature birth (venereal diseases). Symptoms of unripens in newly born animals - Small in size with irregular Hairing and teething - Usually weak, less active or may be die shortly after birth  The umbilical cord Connecting cord running between fetus and placenta and contain 1. 2 umblical arteries. 2. 2 umblical veins. 3. Urachus 4. Vestige of yolk sac (original source of fetal nutrition before placentation). 5. A jelly matrix (WHARTONs JELLY) Species Length Buffalo calf 50 cm Cow calf 30-40 cm Foal 45-90 cm Lambs and Kids 20 cm Puppies and Kittens 8-10 cm Classification of the placenta Placenta - Connection between fetal chorion and maternal endometrium. Anatomical Classification of Placenta 1. Simple diffuse placenta The whole surface of the outer layer of the chorion covered with villi (finger like) embedded in the endometrial crypts and easily separated. - (mare, she-camel- sow). 2. Cotyledonary Placenta - The caruncles in the endometrium lie in apposition with cotyledons and forming the (Placentome). - The inter-cotyledonary areas do not take part in placental functions. - The Placentome arranged in 4 rows (2 dorsal and 2 ventral). Species No. of Placentomes Shape of caruncles Cow 75-120 in both horn Convex and has neck Buffalo 77-129 Convex Ewe 80-90 Cup shaped Goat 140-145 Cup shaped 3. Zonary placenta - The middle part of allanto-chorion covered with villi and interlocked in the maternal pockets(2-7 cm girdle like zone). - The rest of chorion devoid of villi and not share in placental function. - Bitch and Cat. 4. Discoidal Placenta - The attachment between fetal membranes and endometrium occur in a single or multiple disc-like areas (rounded or oval). - Mice, Guinea pig. woman  Histological Classification of Placenta The number of layers separates the maternal and fetal blood consists of 6 intervening layers. According to the number of these layers, the classification of placenta. 1. Epithelio-chorial Placenta - All the 6 layers of tissues covering both the fetal and maternal blood vessels present (simple diffuse). - Mare, she-donkey, she-camel, sow). 2. Syndesmo-chorial Placenta - The fetal tissue present and the epithelium on the caruncles of the maternal tissues is lost. - Cow, buffalo, ewe, she-goat. 3. Endotheliochorial placenta (zonary placenta). - Disappearance of the epithelium and C.T layers of the maternal blood vessels (endothelium of blood vessels of maternal tissue in contact with chorion). - Bitch and Cat. 4. Haemo-chorial placenta (Discoidal placenta) - All 3 layers of maternal blood vessels are absent. - Monkey and Woman. Function of the placenta 1. Respiratory carry O2 to the fetus. 2. Nutrition. 3. Selective absorption of certain elements calcium, phosphorus and iron and vitamins. 4. Storage of certain materials as glycogen and fats. 5. Excretory organs eliminate the waste product. 6. Barrier against infectious poisonous materials (brucella). 7. Convey of antibiotic and antibodies. 8. Endocrine organ secrets hormones as estrogen, progesterone, Relaxin and pituitary-like gonadotrophin and placental lactogen. 9. Fetal membrane can be helpful during pregnancy diagnosis. 10. Synthesis of some constituents (Fructose). 11.Placenta have fetal fluid which - During pregnancy protect fetus against trauma, prevent adhesion of fetus, maintain normal body temp. of fetus, nutrition of fetus. - During parturition form hydrostatic widening cervix, lubricate soft birth way, enable the fetus to change its position or posture.