Presentation on theme: "REPRODUCTION AND HORMONES John D. Harder Department of Evolution, Ecology, and Organismal Biology The Ohio State University Columbus, Ohio 43210 USA."— Presentation transcript:
REPRODUCTION AND HORMONES John D. Harder Department of Evolution, Ecology, and Organismal Biology The Ohio State University Columbus, Ohio USA
Introduction and Outline Modes of reproduction in vertebrates: oviparity, ovoviviparity, and viviparity Three major stages of reproduction (females) (1) seasonal activation, (2) ovulation, fertilization, and embryonic development, (3) hatching/birth, and care of young Key measures of reproductive rate : Clutch size in amphibians, reptiles, birds, and Ovarian and uterine analysis for ovulation rate and litter size in mammals.
Reptile and Amphibian Ovaries
Ovarian Function & Ovulation Ovarian follicles grow and secrete estrogen during the follicular phase of the estrous cycle. Estrus (i.e., female sexual receptivity can be predicted through vaginal smear cytology). Ovulation marks the start of the luteal phase in which corpora lutea (CL) develop from ruptured follicles and secrete progesterone. Counts of CL provide estimates of ovulation rate. Ovarian analysis of yearling does provides a good estimate the percentage of fawns breeding the previous year.
Mammalian Ovary ► Drawing of the mammalian ovary illustrating (in clockwise progression) follicular development (from primordial to Graafian follicle), ovulation, development of a corpus luteum (CL), and regression of the CL. (Copied with permission from Short 1972).
Section Through Vaginal Wall ► Sections through the vaginal wall of the rat and the proportions of 2 types of epithelial cells and leucocytes that are released into the lumen of the vagina during each stage of the estrous cycle. (Copied with permission form Turner and Bagnara (1976) Diestrus: leucocytes Proestrus: basal epithelial cells Diestrus Estrus: keratinized Metestrus: leucocytes epithelial cells and keratinized epithelial cells
Procedure for Slicing ► Procedure for slicing a fixed ovary with a razor blade (A) and a view of the sliced ovary showing an antral follicle and a CL (B)
Endocrinology of Reproduction Testosterone Testosterone, Spermatogenesis & Breeding in males Anterior pituitary secretes gonadotropins: Follicle stimulating hormone (FSH) and luteinizing hormone (LH). Ovarian follicles secrete estrogen prior to ovulation; Elevated estrogen stimulates estrus. Progesterone (P) secreted by CL following ovulation. Periodic elevation of P indicates ovulatory cycles and sustained high level indicate pregnancy. Hormone Concentrations in blood and feces Sampling procedures and hormone assays.
Annual gonadal-reproductive cycle of the red-sided garter snake illustrates a dissociated reproductive pattern (Adapted with permission from Crews and Garstka 1982). Annual Gonadal-Reproductive Cycle
Temporal relationships of estrus and ovulation to circulating levels of progesterone, estrogen, and LH during the estrous cycle of the ewe, which has preovulatory hormone dynamics similar to many mammalian species with spontaneous ovulation (copied with permission from Short 1972). Hormone levels and Estrous Cycle
Birth and Parental Care of Young Nest success in oviparous vertebrates Funnel traps, drift fences, and pitfall traps for capturing dispersing young. Funnel traps, drift fences, and pitfall traps for capturing dispersing young. Mayfield method: estimating nest success in birds Mammals: Litter size and lactation Placental scars in bats, rodents, and carnivores Proportion of females lactating as evidenced in the appearance of nipples and/or milk in the mammary gland.
Uterine Swellings ► Uterine swellings of a pregnant white-footed mouse (Peromyscus leucopus) (A) and postpartum uterine horns compressed between the lid and the inverted base of a Petri dish to reveal placental scars (B)
Biology of Stress Indicators and Measures of Stress Behavioral indicators, food, and water consumption Suppressed immune response and disease Endocrine responses: size of adrenal medulla and cortex Anterior pituitary secretes adrenocorticotropic hormone (ACTH) Concentrations of adrenal corticosteroids (e.g., cortisol and corticosterone in blood and feces). Pitfalls in study design and interpretation of data Variation due to experimental procedures Natural variation in corticosteroids
Control of Reproduction and Wildlife Contraception. Hormonal and immunological methods in females. Effectiveness of progesterone and prostaglandin treatments. OvoControl G Contraceptive Bait for geese. Porcine zona pellucida (PZP) immunization interferes with binding of spermatozoa to the egg. GonaCon Immunocontraceptive for deer. Research programs in Australia on virally-vectored immunocontraception.
Summary Reproductive rate can be assessed at three stages of the reproductive cycle : (1) seasonal activation, (2) ovulation and embryonic development, and (3) hatching/birth and care of young Key measures: Clutch size in amphibians, reptiles, birds and ovulation rate and litter size in mammals Progesterone profiles indicate ovulation and pregnancy Behavior and fecal adrenal corticosteroid levels may provide evidence of stress in captive and wild animals Commercially available contraceptive agents show promise for control of reproduction in geese and deer. Summary Reproductive rate can be assessed at 3 stages of the reproductive cycle: (1) seasonal activation, (2) ovulation and embryonic development, and (3) hatching/birth and care of young Key measures: Clutch size in amphibians, reptiles, birds, and ovulation rate and litter size in mammals Progesterone profiles indicate ovulation and pregnancy Behavior and fecal adrenal corticosteroid levels may provide evidence of stress in captive and wild anaimals Commercially available contraceptive agents show promise for control of reproduction in geese and deer