This lecture corresponds to Chapter 25 in the Marieb 8e textbook.

Overview & Learning Objectives
Lectures Notes & Slides
Lecture Videos
Additional Resources
Noneducational Shenanigans

Overview

Your study of male and female reproductive systems provides the information you need to understand how you, as a species, physically survive from one generation to the next. In terms of the human life cycle, this is the last topic to explore.

The reproductive system includes the study of the phenomenal mechanisms that result in the production of gametes by the testes and ovaries, and the supporting roles of the many male and female organs that ultimately accomplish the overall reproductive goal, production of offspring.

The amount of information is vast and decidedly complicated because of the vital roles played by hormones in processes such as the menstrual cycle and pregnancy.

Use the Complete Anatomy app as well as items under Additional Resources to help you form a firm grasp of the material.

Learning Objectives

Upon completion of this lecture, the student will be able to:

Male Reproductive Strucures

Describe the location, gross and microscopic structure, and function of the testes.
Describe the location, structure, and functions of the ducts and accessory organs of the male reproductive system.
Describe the structure of the penis, and explain the mechanism of erection.
Outline the events of spermatogenesis.

Female Reproductive Structures

Describe the location, structure, and function of the ovaries.
Describe the anatomy of the uterine tubes in terms of their function.
Explain the location of, regions, supportive structures, and layers of the uterus.
Explain the structure of the vagina in terms of its functions.
Describe the anatomy of the female external genitalia.

Lecture Notes & Slides

Lec.15 The Reproductive System

Reading — Ch.25 The Reproductive System

The function of the reproductive system is to produce offspring.
- primary sex organs (gonads)
  - testes in male and ovaries in female
  - produce gametes (sperm in males and ova in females) and sex hormones.
- accessory sex organs — all other reproductive organs.

The Male Reproductive System (pp. 744–755)

The Testes (pp. 744–747)

paired organs located in the scrotum.
The scrotum is the sac of skin and subcutaneous tissue that contains the testes.
The male primary sex organ and the site of sperm production. (Figs. 25.1–25.3)

**Figure 25.1 Reproductive organs of the male, sagittal view.**

Each testis is approximately 2.5 cm in width and 4 cm in height.
Housing the testes outside of the body cavity keeps the testes at a slightly lower temperature than the body, as required for viable sperm production.
- The dartos muscle, cremaster muscle, and pampiniform plexus help regulate the temperature of the testes in the scrotum (Fig. 25.2)

**Figure 25.2 Relationships of the testis to the scrotum and spermatic cord (anterior view).**

Within the scrotum, each testis is
- partly surrounded by a serous sac called the tunica vaginalis (derived from the peritoneum),
- divided into many lobules that contain sperm-producing seminiferous tubules separated by areolar connective tissue. (Fig. 25.2)
Each testis contains seminiferous tubules called the “sperm factories.” (Fig. 25.3)

**Figure 25.3 Structure of the testis.**

- Spermatogenic cells — cells that are in the process of forming sperm.
  - spermatogonia, primary and secondary spermatocytes, and spermatids
  - move toward the tubule lumen as they differentiate into sperm by a process called spermatogenesis.
- Sustenocytes (Sertoli cells)
  - columnar cells within which the spermatogenic cells are embedded
  - provide a variety of important functions
    - form the blood-testis barrier,
    - nourish the spermatogenic cells and move them toward the lumen.
    - secrete testicular fluid (for sperm transport), androgen-binding protein, and the hormone inhibin.
  - Myoid cells
    - smooth-muscle–like cells that surround the seminiferous tubules and help sperm and testicular fluid through the tubules.
  - Interstitial cells (Leydig cells)
    - oval cells in the connective tissue between seminiferous tubules,
      - secrete androgens (mostly testosterone) under the influence of luteinizing hormone (LH) from the pituitary gland.

Male Reproductive Ducts (pp. 747–750)

traces the pathway that sperm cells follow, beginning with the seminiferous tubules and ending with the urethra. (Figs. 25.3–25.6)

**Figure 25.6 Male reproductive structures.**

- Epididymis — site of sperm maturation. (Fig. 25.6)
- ductus (vas) deferens — stores and transports sperm during ejaculation. (Figs. 25.4, 25.6)
- spermatic cord — contains the ductus deferens, blood vessels, and nerves (Fig. 25.5)
  - the inferior part lies in the scrotum,
  - the superior part runs through the inguinal canal.
- urethra — carries sperm from the ejaculatory duct to outside the body. (Fig. 25.6)
- Path of sperm travel
  - seminiferous tubules → straight tubules → rete testes → out of the testes through the efferent ductules → epididymis (head, body, tail) → ductus (vas) deferens → ampulla of ductus deferens → ejaculatory duct → prostatic urethra → intermediate part of urethra → spongy urethra → external urethral orifice
- Epididymis
  - The comma-shaped structure that hugs the posterolateral surface of the testis.
  - The duct of the epididymis, lined with a pseudostratified columnar epithelium with stereocilia, is where sperm gain the ability to swim and fertilize.
  - Ejaculation begins with contraction of smooth muscle in the duct of the epididymis.
- ductus (vas) deferens
  - extends from the epididymis in the scrotum to the ejaculatory duct in the pelvic cavity.
  - During ejaculation, the thick layers of smooth muscle in its wall propel sperm into the urethra by peristalsis.
- spermatic cord
  - covered in fascia and contains the ductus deferens and the testicular vessels.
  - runs through the anterior abdominal wall from the scrotum to the superficial inguinal ring and then continues through the inguinal canal to the deep inguinal ring.
- Urethra
  - runs from the bladder to the tip of the penis, conducts semen and urine to the body exterior.

Accessory Glands (pp. 750–751)

produce secretions that contribute to semen formation.
include the seminal glands, the prostate, and the bulbo-urethral gland (Cowper’s gland)
- seminal glands (seminal vesicles)
  - paired glands that secrete a sugar-rich fluid that forms 60% of the ejaculate. (Figs. 25.1, 25.6)
- prostate
  - surrounds the prostatic urethra;
  - a group of compound glands embedded in a fibromuscular stroma.
  - its secretions constitute about one-third of the volume of semen, and function to clot and liquefy ejaculated semen. (Figs. 25.1, 25.6, 25.7)
- bulbo-urethral (Cowper’s) glands (Figs. 25.1, 25.6)
  - in the urogenital diaphragm
  - secrete mucus into the urethra before ejaculation to lubricate and neutralize this tube for the passage of semen.

The Penis (pp. 751–752)

male organ of intercourse and delivers sperm into the female reproductive tract. (Figs. 25.1, 25.6)

has a root, a body, and a glans covered by foreskin.
Its main nerves and vessels lie dorsally.
Most of its mass consists of vascular erectile bodies—namely, a corpus spongiosum and two corpora cavernosa. Engorgement of these bodies with blood causes erection.

The Male Perineum (p. 752)

diamond-shaped
contains the scrotum, the root of the penis, and the anus.

Spermatogenesis (pp. 752–755)

Spermatogenesis is the formation of sperm, which occurs within seminiferous tubules from puberty until death. (Figs. 25.9, 25.10)

The Female Reproductive System (pp. 755–768)

Functions of the female reproductive system (Fig. 25.12)
- produces ova and sex hormones
- houses, nourishes, protects, and delivers an infant.
- undergoes a menstrual cycle of about 28 days.

The Ovaries (pp. 755–757)

the female primary sex organs and the site of egg cell production. (Figs. 25.12, 25.13)
lie on the lateral walls of the pelvic cavity and are suspended by various mesenteries and ligaments.
Broad ligament — the peritoneum that covers the uterus continues laterally as a double fold known as the broad ligament. It consists of the following parts:
- mesovarium (mesentery of the ovary) — surround the ovaries
- mesosalpinx — surround the fallopian tubes
- mesometrium — surround the uterus
Contained within the broad ligament are the suspensory ligament of the ovary and its continuation, the round ligament of the uterus.
Each ovary is divided into
- outer cortex (follicles containing oocytes separated by connective tissue)
- inner medulla (connective tissue containing the main ovarian vessels and nerves).
One follicle matures each month, releasing one oocyte from puberty to menopause.

**Figure 25.11 Internal organs of the female reproductive system, midsagittal section.**

**Figure 25.13 Photomicrograph of a mammalian ovary.**

The Uterine Tubes (pp. 757–758) (Figs. 25.11, 25.12, 25.14, 25.15)

Also known as the fallopian tubes or oviducts
receive the ovulated oocyte and provide a site for fertilization.
Each uterine tube extends from an ovary to the uterus.
Its regions, from lateral to medial, are the infundibulum, ampulla, and isthmus.
- Fimbriae extending from the infundibulum create currents that help draw an ovulated oocyte into the uterine tube.
The wall of the uterine tube contains a muscularis layer and a folded inner mucosa with ciliated simple columnar epithelium. Both the smooth muscle and ciliated epithelial cells help propel the oocyte toward the uterus.

**Figure 25.12 Internal female reproductive organs.**

**Figure 25.14 Photomicrograph through the uterine tube.**

**Figure 25.15 Peritoneal reflections around the female pelvic organs in situ, superoanterior view.**

The Uterus (pp. 758–760)

a hollow thick-walled organ whose functions are to receive, retain, and nourish a fertilized egg, embryo, and fetus throughout pregnancy. (Figs. 25.11, 25.12, 25.15, 25.16)
Consist of a fundus, a body, and a cervix.
- Cervical glands fill the cervical canal with a bacteria-blocking mucus.
Supports of the uterus are several ligaments, mesenteries, and muscles of the pelvic floor. (Figs. 25.11, 25.12, 25.15)
- Supporting ligaments include
  - Broad ligament
  - Lateral cervical ligament
  - Round ligament
- Most support comes from the muscles of the pelvic floor.
The uterine wall is composed of three basic layers (Figs. 25.12, 25.16)
- Perimetrium —the outermost layer. The outer serosa layer of uterus; equivalent to peritoneum
- myometrium — the muscular middle layer that functions to squeeze the baby out during childbirth
- endometrium — the innermost layer that can be further divided into
  - stratum functionalis — the more superficial functional layer which sloughs off each month (except in pregnancy),
  - stratum basalis —the deeper basal layer which replenishes the functional layer.

**Figure 25.16 The endometrium of the uterus and its blood supply.**

Oogenesis and the Female Menstrual Cycle (pp. 760–766)

Oogenesis, the production of female gametes, starts before birth and takes decades to complete. (Fig. 25.19)

The Vagina (p. 766)

the distensible, muscular tube that connects the uterus to the body’s exterior; it receives the penis and semen during intercourse and acts as the birth canal. (Figs. 25.11, 25.12, 25.20)
The layers of the vaginal wall are
- an outer adventitia,
- a middle muscularis,
- an inner mucosa consisting of an elastic lamina propria and non-keratinized stratified squamous epithelium.
The lumen is acidic.
vaginal fornix — a ringlike recess around the tip of the cervix in the superior vagina.

The External Genitalia and Female Perineum (p. 767)

female external genitalia (vulva)
- the female reproductive structures that lie external to the vagina in the diamond-shaped perineum. (Fig. 25.20), including
  - mons pubis,
  - labia majora and minora,
  - clitoris with its erectile bodies,
  - vestibule containing the vaginal and urethral orifices.
- The mucus-secreting greater vestibular glands and the bulbs of the vestibule (erectile bodies) lie just deep to the labia.
- The central tendon of the perineum lies just posterior to the vaginal orifice and the fourchette.

**Figure 25.20 The external genitalia (vulva) of the female.**

The Mammary Glands (pp. 767–768)

modified sweat glands that are present in both sexes but function only in lactating females. (Fig. 25.21)
Internally, each breast consists of 15–25 lobes (compound alveolar glands) that secrete milk.
The lobes, which are subdivided into lobules and alveoli, are separated by adipose tissue and by supportive suspensory ligaments.
The full glandular structure of the breast does not develop until the second half of pregnancy.
Breast cancers usually arise from the duct system.

Pregnancy and Childbirth (pp. 768–774)

Pregnancy (pp. 768–773)

Fertilization usually occurs in the ampulla of a uterine tube.

Lecture videos

Additional Resources

Additional resources available on 🧪 Lab 18 Male & Female Repro

Noneducational Shenanigans

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