MT - 7: Reproduction Flashcards

Question

TOPIC 95 The endocrinology of parturition; birth Normal birth position:

Answer 1

Normal birth position: - Presentation: Position of the fetus in the birth canal Head first, bottom can cause complications. - Position: Location of the fetal vertebral column at the birth canal. Abdomen down normal position, abdomen up may cause problems: - Deportment: Position of the fetal limbs and the head in relation to the birth canal. Normal is the stretched limbs.

Answer 2

*End of pregnancy: High P4 Low E2 uterus is insensitive of contracting effect of E2 and Oxytocine. Initatory of change: fetal stress. Activation of the fetal hypoyh-hypophysis-adrenocortex axis: *Glucocorticoids+ C19 steroids are synthesized. *Glucocorticoids inhibit P4 synthesis in the placenta and ovary *P4 is converted to E2 due to the activity of 17-alfa-hidroxylase. *In the same time adrogens are converted to E2, activate the phospolyase A2 which stimulates prostahlandin synthesis in the uterus and placenta. Horse: the factors that initiate partuition in the mare have not been elucidated.

Answer 3

* Phase I: The preparatory phase - Opening * Phase II: The phase of contraction * Phase III: After pain * Normal Birth possition - Pressentation - Position - Deportment * End of pregnancy (endocrinology) * Initatory change * Activation of fetal hypoth-hypophysis-adrenocortex-axis - Glucocorticoids + C19 steroids synth - Glucocorticoids inhibits P4 synth (placenta+ovaries) - P4 converted - E2 - Androgens - E2 - Prostaglandin synt in Uterus and placenta - Horse: Partuation have not bin elucidated

Answer 4

In mammals the milk is the only natural way to feed the newborn. It protect against pathogens.

Answer 5

Mammogenesis Lactogenesis Galactopoesis Ejection

Answer 6

Development of gland. The development begins when the animal is an early fetus and proceeds beyond initiation and lactation. 1. Development before birth. Normal Mammogenesis in females around puberty. 2. Development from birth to pregnancy: - Isometric growth: mammary growth rate is similar to the body’s. Mostly fat and connective tissue growth. - Allometric growth: Mammary growth is 3.5times higher that he body’s. Lasts for 2-3 months following puberty. Mostly ductural growth. 3. Development during pregnancy: Further lobuloalveolar development. Happens also due to endocrionological effects: PRL, glucocorticoids, placenta lactogen+ local factors. 4. Development during lactation: further alveolobular growth until peak lactation, then regression happens. Mammary epithelial cells begin to secret. - During dry period: secretory cells go through on regression, preparation for the next lactation phase. - During lactation: Continues growth until peak-lactation. Milk production is related to the number of secretory cells and secretory activity. During lactation the number of dying cells is higher than the number of growing cells. Mammary gland has more secretory cells at the beginning of lactation than at the end of lactation. During dry period: same as last dry period. * Hormonal effects in mammogenesis: - Growth hormone: Development of parenchyma, expression of epithel receptors. - Glucocorticoids: important in the development of ducts+ in the growth of lobulo-alveolar structure. - Estrogen: significant species differences. Stimulates development of parenchyma. Must in cow, not in sheep. IGF important, transmitter of effect. - Progesterone: lobular-alveolar development, especially in later phase of pregnancy. - Prolactin: species differences, it has permissive effect on steroids in cow, not that important in cow, growth hormones can take over. - Placenta lactogen: GH- and PRL- like effect, influence the size of calf, as well as the milking capacity.

Answer 7

* Milk synthesis, milk secretion. * Two stages * Hormonal effects in lactogenesis.

Answer 8

Stage 1: cytological and differentiating of the epithelial cells. Limited milk synthesis. Before parturition. Some milk components make their first appearance in the mammary gland. Formation of colostrums P4 +E2 inhibit the real milk production in Phase 1. Due to gradualchemical and morphological changes . Stage 2: Intensive secretion of milk, and shorter than stage 1. Begins when the inhibitory effects of progesterone on lactogenesis decreases and the stimulation by the very high blood concentrations of prolactin and glucocorticoids occur. Colostrum and then milk synthesis and secretion occur during lactogensis II. Result of abrupt cardiovascular metabolic and secretory changes.

Answer 9

- Progesterone: Antilactogenic - Prolactin: Lactogentic, , Increase milk protein synthesis, controls expression of genes necessary for casein synthesis. - Glucocorticoids: Lactogenic hormones, induce differentiation of dough ER and Golgi apparatus, the differentiation is necessary for Prolactin induced syntheses. - Estrogen: Lactogenic hormone, increase secretion of PRL and other lactogenic hormones from pituitary flans, increase PRL receptors mammary cells. stimulates synthesis of casein and alfa-lactalbumin. - Local factors: PGF2alfa- inhibits milk secretion, reduced during suckling. - Lactose: Decreasing P4 and increasing glucocorticoids and PRL secretions initiates the synthesis of alpha-lactalbumin. Allow more secration of milk. The synthesis of milk is increased. - Role of colostrums: produced in lactogenesis phase. The role of the colostrums is the maternal immunity, nutrient role and laxative effect . - Colostrums contains more protein, fat soluble vitamins, lipids, minerals, water and essential amino acids.

Answer 10

* Maintenance of milk production. Regulated by galactopoietics hormones and local factors. ``` * Hormonal factors: Includes prolactin, Growth hormones, Thyroid hormones and Glucocorticoids. The prolactin is the most important. ``` * Local factors: the nursing stimulus triggers release of galactopoietics hormones which may stimulate the next round of secretory activity. If milk removal is not maintained there is no stimulation of prolactin release.

Answer 11

Milk ejection is a two-component neuro-hormonal reflect: - Neural component= afferent component - and Hormonal component=efferent component. - Oxytocin: do not have mechanical stimulate, but released by visual and auditory signals, there is a contraction of alveolus. - Involution: Regressive transformation of the gland.

Answer 12

* Development of ovary: * Infundibulum: - Role * Magnum: - Role * Isthmus - Role * Uterus: - Role * Uterovaginal sphincter: * Brooding:

Answer 13

- Estrogen: Estrone (E1) and estradiol (E2) takes part in the reproductive process. - Progesterone: P4 level in the plasma increases in the second phase of follicle maturation at the age of 13-15 weeks, together with the increase of LH - LH-FSH After puberty a basal level of LH develops. This is interrupted by preovulatory peaks. 1. Sensitizing phase: Hypothalamic P receptors are increased by the high E and P, so GnRH production increase. 2. Iductive phase: constant rise of preovulatory P peak is enough to stimulate LH secretion by the sensitized hypothalamo-hypophysal photoreceptor system activating the GnRH secretion which increases the production of FSH and LH, resulting in maturation in the gonads.

Answer 14

* Testis: Inside the abdominal cavity. This function as an endocrine gland. * Epididymis: Sperm maturation * Ductus deferens: Main storage of the inactive spermatozoa * Phallus: Two papilla, coming together from each side. Small and has associated lymph glands produce a fluid that is added to the semen. * Spermatogenesis: During puberty, they are matured on the seminiferous tubules, which contribute to the setoli cells. * Sperm: The capital part is not flattened, but cylindrical. - Acrosomal cap and Acrosomal cavity do not separate. - Post-nuclear cap does not evolve. - The neck region is less mobile * Male sexual hormones - The basic sexual gender of the bird is male. - Leydig cells: Synthesizes androgens, - Testis synthesize: estrogen and P4

MT - 7: Reproduction Flashcards

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