Exercise 9: Female reproductive system
Reproductive system overview
Reproductive system is responsible for formation, maturation, and release of gametes and sex hormones. The structures of the reproductive system in males and females develop from the same primordial tissues but then differentiate based on the presence or absence of Y chromosome. The structures formed from the same primordial tissue that have the same functions are called homologous structures. Use table 28.1 in your textbook to summarize the reproductive system homologues and their functions:
|Male organ||Female organ homologue||Function|
Males produce ________ (gametes) in the process of __________________________ and females produce __________ (gametes) in the process of ____________________.
Both male and female reproductive systems become fully functional in puberty. The hypothalamus releases GnRH (_________________ _____________ ___________) which acts on the anterior pituitary to release FSH (__________ ________________ __________) and LH (_________________). These then stimulate gametogenesis and release of sex hormones.
Gametogenesis is the process of gamete formation. Human body is made up of two basic types of cells – somatic cells and gametes, or sex cells. Somatic cells have 23 pairs of chromosomes. 22 pairs are homologous (corresponding) chromosomes, and one pair is pair of sex chromosomes. Gamete formation happens by process known as meiosis. Meiosis is a reduction division, or lessening, where the 23 pairs of chromosomes are separated into 2 sets of 23 individual chromosomes. Meiosis includes meiosis I and meiosis II.
Use figure 28.2 in your textbook to draw stages of meiosis. Use two different colors to represent a homologous pair of chromosomes. Mark important events.
Meiosis I: Meiosis II
Prophase I: Prophase II:
Metaphase I: Metaphase II:
Anaphase I: Anaphase II:
Telophase I: Telophase II:
Mitosis results: (circle correct) 2/4 identical/nonidentical haploid/diploid cells.
Meiosis I results: (circle correct) 2/4 identical/nonidentical haploid/diploid cells.
Meiosis II results: (circle correct) 2/4 identical/nonidentical haploid/diploid cells.
Female Reproductive System
Female gonads are ovaries. Ovaries produce oocytes (female gametes) and sex hormones estrogen and progesterone. Accessory structures of the female reproductive system are fallopian tubes, uterus, vagina, external genitalia, and mammary glands.
See Figure 28.3 in your textbook and be able to identify the following on the figure and on the female reproductive system in Visible Body:
- Uterine tube
- Vesicouterine pouch
- Rectrouterine pouch
- Urinary bladded
- External urethral orifice
- Vaginal orifice
- Labium minus
- Labium majus
See Figure 28.4 in your textbook and be able to identify the following on the figure and on the female reproductive system in Visible Body:
- Ovarian artery
- Ovarian vein
- Suspensory ligament
- External os
- Broad ligament
- Ovarian ligament
Ovarian cycle and oogenesis
Oogenesis begins with a cell known as oogonium. Oogonia form during fetal development and divide by _____________ to form 2 primary oocytes. Primary oocytes enter first phase of meiosis I, ________________, and remain arrested in this phase until puberty. These primary oocytes are surrounded by a single layer of flat cells and this structure is known as primordial follicle. A female has around 1.5 – 2 million primordial follicles at birth. Many of these follicles die off by the time a female reaches puberty. Puberty is marked by hypothalamus releasing gonadotropin-releasing hormone, which will stimulate release of luteinizing and follicle stimulating hormones from the anterior pituitary, and these two hormones will act on the ovaries and stimulate maturation of some of the primordial follicles. Some of the primordial follicles will develop into primary follicles, a few of primary follicles become secondary follicles, some of those will develop into antral follicles. Generally only one antral follicle will become mature follicle (aka Graafian, or vesicular follicle) and this follicle will release oocyte during ovulation. The remnant of the follicle will become corpus luteum, a structure that grows in size and begins to release progesterone and estrogen. These two hormones will promote thickening of the endometrium for optimal implantation if fertilization occurs. If fertilization occurs and implantation occurs, the implanting blastocyst will produce hcg which ill stimulate corpus luteum to release these hormones. If hcg is not present, corpus luteum will cease the hormone release and it will become corpus albicans, which will ultimately be absorbed by the body. This drop in hormones stimulates shedding of the endometrial lining in the process known as menstruation.
Draw the seven main types of follicles as described in the textbook in figure 28.5. Label the following on each type, when applicable:
- Primary oocyte
- Follicular cells 1. Primordial follicle 2. Primary follicle
- Thecal cells
- Zona pelucida
- Granulosa cells
3. secondary follicle 4. Antral follicle 5. Mature follicle
6. corpus luteum 7. Corpus albicans
Histology of Female Reproductive system
Observe the uterus in your textbook, APR, and in the Pictures folder on Blackboard and draw what you see. Notice the presence of the endometrial glands and the transition from endometrium to smooth muscle.
Observe the ovary in your textbook, APR, and in the Pictures folder on Blackboard and draw what you see. Focus on the cortex area as this is where you will be able to see the various follicles.
Exercise 10: Male reproductive system
Male Reproductive System
The main organs of the male reproductive system are testes. Testes produce gametes, known as sperm, and sex hormone testosterone. Accessory structures include scrotum, seminal vesicles, prostate gland, bulbourethral gland, and penis.
Testes are located in scrotum, a skin-covered sac that provides slightly cooler environment for ideal sperm formation. Underneath the skin is the superficial fascia and a thin flat dartos muscle.
See Figure 28.14 in your textbook and be able to identify the following on the figure and on the male reproductive system in Visible Body:
- Urinary bladder
- Pubic symphysis
- Ductus deferens (vas deferens)
- Urogenital diaphragm
- Glans of penis
- Ampulla of vas deferens
- Seminal vesicle
- Ejaculatory duct
- Prostate gland
- Bulbourethral gland
See Figure 28.15 in your textbook and be able to identify the following on the figure and on the male reproductive system in Visible Body:
- Testicular artery
- Testicular vein
- Urinary bladder
- Spermatic cord structures:
- Vas deferens
- Pampiniform plexus (venous plexus)
- Testicular artery
- Testicular nerve
- Layers of the spermatic cord
- External spermatic fascia
- Cremaster muscle
- Internal spermatic fascia
- Dartos muscle
Testes and spermatogenesis
Testes are oval shaped organs that serve as a site of spermatogenesis and production of testosterone. Tunica albuginea encloses the testes and its projections, called septa, divide the testes internally into lobules. Each lobule houses up to 4 seminiferous tubules where sperm develop. Between these tubules are Leydig cells which produce testosterone. Each seminiferous tubule consists of Sertoli cells, which support and nourish the dividing germ cells. Basic hormonal pathway is the same as in females: hypothalamus begins secreting gonadotropin releasing hormone in puberty, this stimulates production and release of luteinizing and follicle stimulating hormone from anterior pituitary, and this stimulates testes to begin spermatogenesis. Germ cells will enter spermatogenesis and become sperm. Spermatogenesis becomes with a cell known as spermatogonia. Spermatogonia divide by mitosis. One of the cells becomes a primary spermatocyte, while the other cell becomes another spermatogonium. This allows spermatogenesis to continue virtually indefinitely. Primary spermatocytes enter meiosis I, and divide into two secondary spermatocytes. Each secondary spermatocyte will enter meiosis II and after second division will become spermatids. Spermatids aren’t sperm yet, they still have a round shape. The final process, known as spermiogenesis, will result in the sperm taking on its typical shape – small amount of cytoplasm surround the nucleus in the head of the sperm, mitochondria migrate to the region known as midpiece, and flagellum develops. The tip of the head has acrosome cap, and this region contains chemicals that will help the sperm penetrate corona radiata and zona pellucida surrounding the oocyte.
See Fig. 28.18 and be able to identify the following structures:
- Leydig cells (interstitial cells)
- Sertoli cell
- Primary spermatocyte
- Secondary spermatocyte
- Acrosome cap nucelus
Histology of Male Reproductive system
Testes and epididymis
Observe the testes and epididymis under the microscope and draw what you see at 100x. Find the region where testes and epididymis meet. Label testes and epididymis.
Testes, epididymis, 100x
Observe the sperm under the microscope and draw what you see at 400x.