Sperm Development and Spermatogenesis

Sperm Development and Pathway

• Sperm develop in seminiferous tubules.
• The pathway is: seminiferous tubules > rete testes > efferent ductules > epididymis > ductus deferens.
• After the ductus deferens, sperm travel through ampulla, ejaculatory duct, and urethra.

Spermatogenesis Stages

• Spermatogenesis sequence: Type B daughter cell > growth > primary spermatocyte > meiosis I > secondary spermatocyte > meiosis II > spermatids.

Spermiogenesis

• Spermiogenesis is the production of tailed sperm.
• Mitochondria multiply and accumulate within sperm during spermiogenesis.

Meiosis Outcome

• Meiosis produces haploid gametes, genetically distinct from each other.

Milk Production Hormone

• Prolactin stimulates milk production.

Prenatal Nutrition

• Uterine milk is the only prenatal nutrition before blastocyst implantation.

Sperm Storage

• Mature sperm are stored in the epididymis (tail) for 40-60 days. If unused, they are reabsorbed.

Homologous Structure

• Labia majora are homologous to the scrotum.

Testis Development

• The SRY gene on the Y chromosome codes for the testes-determining factor (TDF).
• TDF stimulates the development of the male reproductive system.
• Testosterone is secreted to develop mesonephric ducts into male anatomy at 8-9 weeks.

Emission Stage

• Sympathetic signals initiate peristalsis to propel sperm through the ducts during emission.

Female Reproductive Anatomy Homologue

• The female structure homologous to the male scrotum is the labia majora.

Additional Details (Page 2)

• Temperature Regulation: The cremaster muscle relaxes to suspend the testes further from the body, regulating temperature.
• Type B Daughter Cells: These cells are destined to become sperm.
• Bulbourethral Gland Secretion: Produces a clear, slippery secretion that neutralizes urine acidity.
• Primary Sex Organ Example: Testes.
• Egg Penetration: Sperm first penetrates granulosa cells, then the zona pellucida of the egg.
• Sperm Penetration and Calcium: Sperm penetration releases sodium, causing a fast block (depolarization) in the egg membrane.
• Embryonic Disk Formation: The inner cell mass (embryoblast) forms the embryonic disk.
• Implantation Hormone: The trophoblast secretes human chorionic gonadotropin (hCG) to stimulate the corpus luteum and progesterone production.
• Respiratory Tract Mucosa: The endoderm forms the majority of the mucosal epithelium of the respiratory tract.

Additional Details (Page 3)

• Embryo to Fetus Transition: The presence of all organs at the end of 8 weeks marks the start of the fetal stage.
• Prenatal Nutrition Source: Trophoblastic nutrition is the primary source of nutrition for the first week after implantation.
• Placenta Function: The placenta does not function exclusively as a nutritive organ; it also is responsible for excretory and respiratory functions within the woman.
• Earliest Puberty Sign (Female): Thelarche (breast development) is the earliest noticeable sign of puberty in females.
• Female Reproductive Development: The female reproductive tract develops from paramesonephric (Müllerian) ducts; the male tract develops from mesonephric (Wolffian) ducts.
• Hormonal Regulation of Pregnancy: The major hormones involved in pregnancy are primarily secreted by the placenta.
• Reproductive Response Stages: Excitement, Plateau, Orgasm, Resolution.
• Female Copulatory Organ: Vagina.
• External Genitalia Differentiation: External genitalia differentiate at 12 weeks of development.

Additional Details (Page 4)

• Ovulation Outcome: Ovulation leads to the formation of the corpus luteum, which releases progesterone.
• Labor Contractions Hormone: Oxytocin causes uterine contractions during labor.
• Connective Tissues and Genital Ducts: Mesoderm is the germ layer responsible for some connective tissues, ureters, and genital ducts.
• Luteal Phase: Occurs from day 15 of the menstrual cycle to 26, marked by endometrium thickening under progesterone influence.
• Fertilization Product Sequence: Zygote, blastocyst, embryo, fetus.
• Hormone Impact on Pregnancy: FSH does not significantly influence the pregnancy period.
• Pregnancy Hormone Source: The placenta is the major source for hormones within pregnancy

Additional Details (Page 5)

• Colostrum Composition: Colostrum forms in late pregnancy and is similar to breast milk, but with more protein.
• Reproductive Tract Development: Females have paramesonephric (Müllerian) ducts; males develop from mesonephric (Wolffian) ducts.
• Oocyte Survival: Fertilization by two sperm significantly decreases the chances of oocyte survival.
• Ovulation Pattern: Ovulation typically alternates between the left and right ovaries in monthly cycles.
• Menstrual Cycle Phases: The premenstrual phase consists of tissue necrosis and menstrual cramps. - Menopause and Climacteric: The climacteric marks a change in hormone production (accompanied by menopause).
• Meiosis II Product: Meiosis II of spermatogenesis results in four genetically unique daughter cells, each with 23 non-replicated chromosomes.
• Erection Structure: Blood from the testicular arteries fills the corpus cavernosum during an erection.
• Embryonic Period: Organ systems first form in the embryonic period.

Additional Details (Page 6)

• Nervous System Development: The nervous system and sense organs develop in the embryo.
• Urogenital Development: The endoderm forms the liver, the gallbladder, and the pancreas.
• Heart Structure: The foramen ovale connects the fetal left and right atria within the heart.
• Blood Cell Origin: The first blood cells arise from the yolk sac.
• Organogenesis: Neurulation is the first major event during organogenesis.
• Fetal Development: The placenta forms by week 12; approximately 266 days from fertilization marks full-term development.
• Labor Initiation Hormone: Cortisol initiates labor in the fetus.

This quiz covers the complex processes of sperm development, including the pathway of sperm through the male reproductive system and the stages of spermatogenesis. It also discusses the roles of hormones and nutrition in reproduction, providing a comprehensive overview of male gamete production.