In-Depth Notes on Male and Female Reproductive Systems

Introduction to Male and Female Reproductive Anatomy

• Overview of reproductive organs is fundamental in understanding gametogenesis and fertilization.

Mitochondria and Gametes

• Mitochondria are found in the mid-piece of sperm and provide energy for motility, critical in reaching the egg.

• Sperm's primary role is delivering genetic material to an egg; it is significant to note that only the sperm’s nucleus penetrates the egg, not the tail.

Male Reproductive System

Gonads

• Testes are the male gonads responsible for sperm production.

• Sperm development occurs in seminiferous tubules within the testes.

Sperm Pathway

1. Epididymis: Stores and matures sperm.

   • Composed of a head, body, and tail.

2. Vas Deferens (Ductus Deferens): Transports sperm from the epididymis to the ejaculatory duct.

Accessory Glands

• Seminal Vesicles: Produce seminal fluid, contributing about 60% of the total semen volume.

• Prostate Gland and Bulbourethral Glands also contribute to seminal fluid composition, providing nutrients and a suitable environment for sperm.

Erectile Tissue

• Corpora Cavernosa: Two cylindrical structures that fill with blood during arousal, causing erections.

• Corpus Spongiosum: Surrounds the urethra and keeps it open during erection.

• Root of Penis: Consists of two crura (crus of corpora cavernosa) and the bulb (part of the corpus spongiosum).

Female Reproductive System

Ovaries and Follicle Development

• Ovaries are the female gonads where oogenesis (egg development) takes place. Each female is born with a finite number of primordial follicles containing primary oocytes.

• Hormonal signals (from FSH and LH) trigger development and maturation of these follicles through stages:

  • Primordial Follicle ➔ Primary Follicles ➔ Secondary Follicles ➔ Graafian (Mature) Follicle.

  • Secondary Oocyte is released during ovulation.

Hormonal Control

• LH (Luteinizing Hormone): Triggers ovulation and helps transform the ruptured follicle into the corpus luteum, which secretes progesterone to maintain the uterine lining.

• FSH (Follicle Stimulating Hormone): Promotes follicle growth and regulates menstrual cycles.

Oogenesis Process

• The primary oocyte undergoes meiosis; upon ovulation, it completes meiosis to become a secondary oocyte. This gives rise to one functional egg and polar bodies, which degenerate.

• Fertilization, when sperm penetrates the egg, triggers the completion of meiosis II in the oocyte, leading to the formation of a zygote (fertilized egg).

Pathway of Sperm and Egg

• Sperm must travel through the female reproductive tract to reach and fertilize the egg in the ampulla of the fallopian tube, navigating via peristaltic movements against the ciliary action of the tubes.

Menstrual Cycle Overview

• 28-Day Cycle: Encompasses follicular and luteal phases. Key events include:

  • Follicular Phase: Development of follicles and rising levels of estrogen.

  • Ovulation: Triggered by a surge in LH.

  • Luteal Phase: Corpus luteum formation and production of progesterone, preparing the uterus for potential implantation.

Changes During Menstrual Cycle

• The endometrium (uterine lining) thickens in preparation for implantation but is shed during menstruation if fertilization does not occur.

Additional Male Structures

• Spermatic Cord: Connective tissue sheath that encompasses the vas deferens, blood vessels, and nerves supplying the testes.

Summary Points

• Understanding reproductive anatomy is crucial for grasping concepts of fertilization and reproductive health.

• Key components include the series of ducts in males that transport sperm, as well as the ovarian follicles and hormonal cycles in females.