1. Organismal Development Part 3
Male Animals

2. Important concepts from previous units:
Mitochondria provide chemical energy (ATP) for cells by performing cellular respiration using sugars.
Pheromones are a form of long distance communication between organisms using chemical attractants.
Matter and energy for growth and development comes from the environment.

3. Mitochondrion Intermembrane space Outer membrane Free ribosomes in the.
Mitochondrion
Intermembrane space
Outer
membrane
Free
ribosomes
in the
mitochondrial
matrix
Inner
membrane
Cristae
Matrix
Mitochondrial
DNA
100 nm

4. Phermones

5. Hermaphrodites – Organisms possessing both sexual organs
Hermaphrodites – Organisms possessing both sexual organs. Most species cannot self-fertilize.
Sequential Hermaphrodites - The organisms can change sexes based on environmental pressures.
Protogynous (“proto”; “alpha” means “first”; “gyn” refers to females) The Alpha female becomes male.
Protandrous – (“andro” refers to males) The Alpha male becomes female.
This guarantees that the most fit genes are passed on to the next generation.

6. Earthworms are hermaphrodites

7. Protogynous (Male is blue)

8. II. Mechanisms for sexual reproduction:
A. Fertilization - The fusing of haploid sperm and egg to create a diploid zygote.
1. Externally – Fertilization occurs outside the body. (This occurs in fish and amphibians.)
2. Internally – Fertilization occurs internally. (This occurs in most animals including reptiles, birds, and mammals.)

9. External Fertilization

10. Internal Fertilization required

11. III. Pheromones – Chemicals that are released into the outside environment to attract a mate or mark a territory.
MATE ATTRACTANTS

12. Spermatogenesis – This is the making of sperm.
Spermatogonia – These are the cells that make sperm (4 of them) by undergoing the two divisions meiosis.
Sperm structure:
The Head contains the:
Nucleus - Site of the DNA. – It has 23 Chromosomes in humans. (It is n- haploid.)
Acrosome – The tip of the head that contains digestive enzymes used to eat through the protective jelly surrounding the female egg.
Midpiece – This part contains mitochondria for making energy (ATP) to power the swimming of the tail.
Tail – It is a flagella composed of microtubules from the cytoskeleton.

14. Spermatogenesis Epididymis Seminiferous tubule Testis Cross section
of seminiferous
tubule
Spermatogonium
Mitotic division, producing
large numbers of spermatogonia
Sertoli cell
nucleus
Differentiation and onset of meiosis I
Primary spermatocyte
(in prophase of meiosis I)
Meiosis I completed
Secondary spermatocyte
Meiosis II
Lumen of
Seminiferous tubule
Early
spermatids
Spermatids
(at two stages of
differentiation)
Differentiation
Sperm cells
Neck
Head
Midpiece
Tail
Plasma membrane
Acrosome
Nucleus
Mitochondria

15. Androgens – These are the male hormones.
Male hormonal pattern
Androgens – These are the male hormones.
Primary sex characteristics – This refers to the ABILITY to make sperm. (This occurs at adolescence.)
Secondary sexual characteristics – This are the “traits” of men such as facial hair, muscle mass, deep voice.
Secondary characteristics start at puberty with the release of GnRH, from the hypothalamus, to the pituitary and continues until death usually. (This is why it is non-cyclic.)
These hormones are not released in a cyclic pattern like female hormones are.

16. Secondary Sexual Characteristics