Reproductive Physiology

• Aristotle proposed that the fetus originates from menstrual blood (384-322 BC).
• Fallopius discovered and described the oviduct in 1562.
• Coiter discovered and described the corpus luteum in 1573.
• De Graaf discovered and described the antral follicle in 1672.
• Van Leeuwenhoek discovered and described spermatozoa in semen in 1677.
• Spallanzani hypothesized that spermatozoa were the fertilizing agents and artificially inseminated a dog successfully in 1780.
• Dumas proved that spermatozoa were the fertilizing agents in 1825.

Asexual Reproduction

• Asexual reproduction involves mitotic division, essentially cloning.
• Offspring are genetically identical to each other and the parent.
• In vertebrates, parthenogenesis is a form of asexual reproduction.
• Parthenogenesis is when germ cells differentiate without sperm into a genetically identical organism.

Vertebrate Parthenogenesis

• Females produce eggs that develop without fertilization.
• This occurs in some sharks, birds, and fish.
• Parthenogenic animals are typically female due to inheriting only the mother's chromosomes, resulting in female sex determination (XX).

Sexual Reproduction

• Germ cells produce gametes (sperm and oocyte).
• Gametes contain half the genetic material of each parent.
• Sexual reproduction leads to increased genetic variation.
• Benefits include adaptation to environmental changes, genetic improvement, and perpetuation of the species.

Rat Reproduction Example

• Rats ovulate every 4-5 days.
• Gestation period is 21 days.
• Lactation lasts about 20 days.
• They deliver 10-12 pups per litter.
• Birth triggers ovulation.
• Puberty occurs at 30-35 days.
• Rats can produce pups every 3 weeks.

Importance of Controlling Reproduction

• High reproductive efficiency in food animals leads to more food and profit.
• It can also cause overpopulation issues like animal damage and resource depletion.
• Low reproductive efficiency conserves resources and retards population growth.
• It may also result in suboptimal production of animal products and less profit.

Opportunities in Reproductive Physiology

• Managing endangered species
• Pharmaceutical applications
• Improving companion animal health
• Studying lactation and nursing
• Contributing to human medicine (Ob/Gyn)
• Addressing reproductive health issues and diseases
• Advancing genetics
• Developing assisted reproductive technologies
• Improving veterinary medicine
• Enhancing domestic animal (food) production
• Researching molecular biology
• Studying endocrinology (hormones)
• Focus on gamete preservation

Advances in Modern Reproductive Physiology

• In vitro fertilization (IVF)
• Embryo transfer
• Pregnancy detection methods
• Contraception (released 50-60 years ago)
• Estrous synchronization
• Frozen semen
• Artificial insemination
• Enos J. Perry brought AI to Rutgers University
• Sex selection

XY Inc.

• Located in Fort Collins, CO and licenses technology to sort semen.
• Specializes in research, development, and commercialization of XY® sex selection technology.
• This applies to mammals including cattle, horses, pigs, and endangered species.
• X chromosomes determine females and Y chromosomes determine males.
• X sperm have greater DNA content than Y sperm

XY Inc. Sex Selection

Sperm Selection process

• Sperm DNA is fluorescence-labeled.
• Sperm is sorted by flow cytometry.
• More fluorescence indicates "X" sperm.
• Less fluorescence indicates "Y" sperm.

Human Sperm Sorting

• Microsort, Inc. is located in Fairfax, VA.
• As of January 2008, had facilitated 1339 pregnancies.
• X-sort® enriches X-bearing sperm by 85%.
• Y-sort® enriches Y-bearing sperm by 73%.
• Aims to balance families and prevent X-linked diseases in AMAB offspring.

Historical Pregnancy Detection

• Old method: Inject 'suspected' human serum or urine into a female rabbit, after 2-3 days, sacrifice the rabbit, observe ovaries for ovulation.
• Human chorionic gonadotropic (hCG) is detectable in blood and urine early in pregnancy.
• Rabbits are induced ovulators, hCG induces ovulation.
• Ovulation indicated pregnancy, no ovulation indicated no pregnancy.

Modern Pregnancy Detection

• Home pregnancy tests (mid-1970s) use monoclonal antibodies to detect hCG in urine.
• An hCG-antibody complex generates a color reaction.
• A color change indicates a positive pregnancy test.
• hCG binds to monoclonal antibodies.

Reproduction: The Future

• There's a demand for new solutions to solve reproductive problems.
• A strong understanding of reproductive physiology is needed to apply new technologies and develop these solutions.

Asexual Reproduction: Cloning Mammals

• Dolly the sheep was cloned in February 1997.
• Dolly was the first mammal cloned from an adult cell.
• The process involved transferring the nucleus from an adult cell to an egg with its DNA removed.
• The success rate was low: 277 eggs/nuclei transferred yielded one live birth.
• Dolly was the first clone confirmed to breed normally and produce healthy offspring.
• She conceived naturally and gave birth to Bonnie in 1998 and triplets in 1999.
• Dolly died in February 2003 and is on display at a Scottish museum.

Introduction to Theriogenology

• Theriogenology is a branch of veterinary medicine focused on reproductive health in both males and females.
• It includes clinical practices related to obstetrics (OB), gynecology (GYN), and andrology.
• Obstetrics (OB) deals with pregnancy, childbirth, and the postpartum period.
• Gynecology (GYN) focuses on the health of the female reproductive system.

Anatomy of the Female Reproductive Tract

• The female reproductive tract includes ovaries, oviducts (Fallopian tubes), uterus, cervix, vagina, and external genitalia.

Ovaries

• Located near the kidneys.
• Functions include the production of gametes (ova) and hormones (steroid and protein hormones).
• Structures include the germinal epithelium (potential location for ovarian cancer), tunica albuginea, cortex (containing follicles and corpora lutea/albicans), and medulla (housing vasculature, nerves, lymphatics, and connective tissue).

Uterine and Tubular Structures

• The uterine body and horns support pregnancy.
• The cervix contains structures like pulvini and spiral folds, which help in closing and sealing.

Equine Ovary

• Cortex and medulla are reversed compared to other species.
• Ovulation occurs at the ovulation fossa.
• Only follicles, not the corpus luteum, can be palpated rectally.

Connective Tissue in the Reproductive Tract

• The peritoneum lines the abdominal cavity.
• During embryonic growth, the reproductive tract becomes encapsulated by the peritoneum.
• It forms the broad ligament to support the uterus and connects to the pelvic walls.
• Broad ligament houses vascular supply, lymphatics, and nerves

Broad Ligament Components

• Mesovarium covers the ovaries.
• Mesosalpinx covers the oviduct and helps orient the infundibulum.
• Mesometrium covers the uterus, supports the uterine horns and body, and is the largest part of the broad ligament.

Cellular Structure of Tubular Portions

• Serosa is the outermost layer of flattened cells.
• Muscularis contains double smooth muscle layers (outer longitudinal and inner circular), aiding in contractions.
• Submucosa contains blood vessels, nerves, and lymphatics, supports the mucosa, and varies in thickness.
• Mucosa lines the lumen, secretes mucus, and has different cell types depending on location.

Folliculogenesis

• Folliculogenesis is the process where immature follicles develop into more advanced follicles and become candidates for ovulation.

Follicle Cell Types

• Granulosa Cells (GC): Direct oocyte development, steroidogenesis, and follicular fluid secretion; avascular
• Theca Cells:
• Externa - outermost layer of antral follicle; provides structural integrity and support (contains CT)
• Interna - flattened spindle-shaped cells along basement membrane of antral follicle and produce androgens

Types of Follicles

• Primordial Follicles: Most immature, non-growing pool of follicles, females are born with a set number of follicles, oocyte w/ single layer of squamous cells
• Primary Follicles: Growing pool, oocyte with single layer of cuboidal cells, Either (1) develop further; or (2) degenerate (atresia)
• Secondary Follicles: 2 or more layers of granulosa cells (GC), No antrum, Contains zona pellucida (thick translucent layer surrounding oocyte)
• Tertiary or Antral Follicles: Fluid-filled antrum, multiple layers of granulosa cells and theca cells external and internal
• Atretic: degenerating follicles - only 0.1% of ovarian follicles ovulate, the rest (99.9%) die through atresia

Corpus Luteum (CL)

• After follicle rupture a corpus hemorrhagicum forms (bloody body).
• Granulosa and theca cells differentiate into luteal cells.
• Produces progesterone.
• Transitions into Corpus Albicans (a scar-like structure) after its functional period.

Ovulation

• Follicle ruptures
• Ovum released
• Corpus hemorrhagicum forms

Polycystic Ovarian Syndrome (PCOS)

• Characterized by multiple small cysts due to unruptured follicles.
• Results in elevated androgen levels, infertility, and insulin resistance.

Ovarian Cancer Causes

• Two main theories exist regarding their causes:
• Theory 1: Ovarian surface epithelium (OSE)
  • Repeated ovulation causes mutations due to wound and repair cycles, common in postmenopausal (PM) women.
  • Gonadotropin stimulation (FSH/LH action on OSE) induces tumor formation.
• Theory 2: Fallopian tube epithelial (FTE) cells that have lost function p53 form serous tube intraepithelial cancers (STIC).
  • Over time (6-8 years) these cancerous cells seed the ovary and distant metastases

Cancer Treatments and Developments

• Clinical trials are exploring the efficacy of salpingectomy (removal of fallopian tubes) to reduce the incidence of ovarian cancers without removing the ovaries.

The Biological Clock Test

• Developed in England to predict the number of eggs women have in their ovaries (Jan 2006).
• Eggs Measured by ORI (Ovarian Reserve Index) - # of eggs in ovary
• Measured by blood levels of three hormones: Inhibin B, Anti-Mullerian hormone, and Follicle stimulating hormone. -Inhibin B & AMH decline as ovaries age & FSH increases with age
• Not a fertility test, used to decide how long to delay conception, cost around $300-400
• Ideal antral follicle count (AFC) by Ultrasound Testing is 15-20/ two ovaries

Explore key concepts in reproductive physiology including fertilization, parthenogenesis, and the benefits of sexual reproduction. Test your knowledge of important discoveries and reproductive strategies. Ideal for students of biology and related fields.