Sex reversal refers to the process by which an organism undergoes a change in its sexual phenotype. Typically involving the transformation of primary and/orsecondary sexual characteristics from one sex to another. This can occur through genetic, hormonal, or environmental influences, leading to the development of reproductive organs and features that are atypical for the organism's genetic sex

1. University of Chakwal, Pakistan

2. Hormonal Sex Reversal
Department Of Zoology
Presented by : Hina Tariq
REG.NO: 20M-UOC/ZOL-36
BS Zoology
Session 2020-24
Subject : Endocrinology
Submitted to: Dr Syeda Nadia Ahmad

3. Hormonal Sex
Reversal
• Introduction
• Hormonal sex reversal
• Sex reversal
• Types of sex reversal
• Artificial sex reversal
• Natural sex reversal
• Significance of hormonal sex reversal
• Disorders of hormonal sex reversal
• Androgen insensitivity syndrome
• Congenital adrenal hyperplasia
• Conclusion

4. Introduction:
Sex reversal refers to the process by which an organism undergoes a change
in its sexual phenotype. Typically involving the transformation of primary
and/orsecondary sexual characteristics from one sex to another. This can
occur through genetic, hormonal, or environmental influences, leading to
the development of reproductive organs and features that are atypical
for the organism's genetic sex.(Higuchi, etal., 2019)

5. • Example :
• In clownfish groups, when the dominant female dies, the largest
male undergoes a physiological transformation, becoming a female.
• This sex reversal ensures the continuation of the social group's
reproductive cycle.(Higuchi, etal., 2019)

6. Types of sex reversal
Artificial
sex
reversal
Natural sex
reversal

7. Content Natural sex reversal Artificial sex reversal
Initiating factor Internal factors or
environmental
Human intervention
Common methods Genetic switches
Sequential
hermaphroditism
Hormones genetics
modifications ,
temperature control
Control Limited human control Controlled by specific
intervention
Purpose Natural adaptation
Population dynamics
Aquatic , research ,
conservation

8. Example of Natural Sex Reversal
Goby fish are known for their ability to undergo natural sex reversal, changing from male to
female. Initially, social and environmental factors, such as population density, social
structure, or changes social hierarchy, can trigger the transformation.
Under the influence of these social and environmental factors, the endocrine system of
the goby fish responds by altering the production and regulation of various
hormones, including androgens (e.g., testosterone) and estrogens (e.g., 17β-estradiol).
The shift in hormonal balance ultimately affects the development and differentiation of the
gonads, leading to the transformation of testes into ovary. (Smith, J. A. , 2019)

9. Mechanisms of hormones in natural sex
reversal
Gonadal
Development
Hormonal
Signaling
Pathways
Gene
Expression
Regulation
Cellular
Differentiation
and
Proliferation

10. Significance of hormonal sex reversal
Aquaculture
Production
Population
management
Population Control
Research and
Development
Conservation
Efforts

11. 1. Androgen insensitivity syndrome
Androgen insensitivity syndrome (AIS) is a condition that affects sexual development
before birth and during puberty. Individuals with AIS are genetically male, with one X
and one Y chromosome (46,XY), but their bodies are unable to respond to male sex
hormones (androgens). This results in varying degrees of feminization of the external
genitalia and the inability to develop typical male secondary sexual characteristics.
Symptom
Underdeveloped or absent male genitalia at birth, Development of female
secondary sexual characteristics during puberty, such as breast development and a
female distribution of body fat, Absence of menstruation, Infertility due to the absence of
a uterus and ovaries.(Nishimura, T., & Tanaka, M., 2018)

12. Fig 1.1:Androgen insensitivity syndrome
https://image.app.goo.gl/wQQRQfs3cLpJY6Cf8

13. • Congenital adrenal hyperplasia
Congenital adrenal hyperplasia (CAH) refers to a group of genetic disorders that affect
the adrenal glands' ability to produce hormones. This condition typically arises due to a
deficiency of certain enzymes involved in the production of cortisol and aldosterone.
In newborns, symptoms may include ambiguous genitalia in females, which can make it
difficult to determine the baby's sex at birth. In older children and adults, symptoms may
include early onset of puberty, rapid growth, excessive body hair, menstrual
irregularities in females, and infertility.
Treatment typically involves hormone replacement therapy to correct the hormonal
imbalances and maintain normal growth and development.(Speiser. P, W&White P. C., 2002)

14. 5 Alpha Reductase Deficiency:
5-alpha-reductase deficiency is a genetic condition that affects the development of the
external sex organs before birth.
This condition is also known as 5-ARD or 5-alpha-reductase 2 deficiency.
It is a type of disorder of sex development (DSD) that affects individuals with a male
genotype (XY) out may have ambiguous or female external genitalia at birth.
Symptoms
Symptoms can include varying degrees of under virilization, such as ambiguous genitalia,
micropenis, or hypospadias (a condition where the opening of the urethra is on the underside
of the penis).
Some individuals may also develop male secondary sexual characteristics at the time of
puberty, but with varying degrees of virilization.(Okeigwe, I., & Kuohung, W. , 2014)

15. Fig 1.2:5 Alpha Reductase Deficiency & Congenital adrenal hyperplasia
https;//images.app.goo.gl/nPM311KjeFmZKiM9A

16. • Treatment
Treatment options often involve hormone therapy to help
stimulate virilization and promote the development of male
secondary sexual characteristics.
Psychological support and counseling are also crucial to help
individuals and their families navigate the challenges associated
with the condition.
Early diagnosis and appropriate management are important for
ensuring optimal physical and psychological well-being.
(Okeigwe, I., & Kuohung, W., 2014).

17. Conclusion:
Hormonal sex reversal refers to the phenomenon where the sexual
characteristics of an organism are altered due to changes in
hormone levels. It can occur naturally in certain species or be induced
through various environmental. The conclusive understanding is that hormonal
sex reversal is a complex process influenced by genetic, hormonal, and
environmental factors, and its implications can vary widely depending on
the specific context and species involved.

18. References:
1. Okeigwe, I., & Kuohung, W. (2014). 5-Alpha reductase deficiency: a 40-year retrospective review.
Current opinion in endocrinology, diabetes and obesity, 21(6), 483-487.
2. Nishimura, T., & Tanaka, M. (2018). Hormonal sex reversal: Understanding the significance for
reproductive biology and aquaculture. Reviews in Fisheries Science & Aquaculture, 26(4), 431-442.
3. Smith, J. A. (2019). Understanding sex reversal in amphibians. Journal of Herpetology, 35(2), 123-135
4. Higuchi, M., Hiramatsu, N., Sato, T., Fukami, H., & Morohashi, K. (2019). Effects of an androgenic
steroid, 17α-methyltestosterone, on gonadal sex differentiation and germ cell development in the
medaka, Oryzias latipes. Aquatic Toxicology, 213, 105221.
5. Hattori, R. S. (2016). Sex determination and sex differentiation in fish: an overview of genetic,
physiological, and environmental influences. Aquaculture, 450, 4-20.

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