‘Male-typical development results from prenatal or neonatal exposure to testicular hormones, whereas female-typical development happens in the absence of testicular hormones, according to the classical model of hormonal influences on mammalian sexual differentiation.’

1. University of Chakwal, Pakistan

3. Topic: Role of Hormones During Gender
selection
Department of Zoology
Presented by: Hina Samreen
Roll no# UOC-BSZOL-F2020/26
BS Zoology
Session: 2020-2024
Subject: Endocrinology
Instructor Name: Dr. Syeda Nadia Ahmad

4. Introduction
‘‘Male-typical development results from prenatal or neonatal exposure to testicular hormones,
whereas female-typical development happens in the absence of testicular hormones, according
to the classical model of hormonal influences on mammalian sexual differentiation.’’
Fig 1.1 Sex determination and sexual differentiation
https://images.app.goo.gl/dAtZwgYYJbL21q2M6
 Gender selection depends upon:
 Chromosomal Determination
 23rd pair of chromosome
 In early stage of development:
 Both male and female have reproductive potential
 The wolfian duct Male reproductive organs
 Mullerian duct Female Reproductive organ

5.  Chromosomes determine gender: XX for females, XY for males.
 Natural gender selection is random, with roughly a 50-50 chance.
 Scientific methods like PGT during IVF can identify embryos' gender.
Hormonal Influence:
 Hormones, especially testosterone, influence the development of male traits during fetal
development.
 AMH is a hormone produced by cells in developing egg sacs (follicles) in the ovaries. Its main
role is in inhibiting the development of male reproductive organs during fetal development.
 In females, the presence of two X chromosomes (XX) leads to the production of AMH,
preventing the formation of male structures.

6. 1. Wolffian Duct:
‘‘The Wolffian duct is a structure present in the early embryo that has the potential to develop into male
reproductive organs under the influence of certain hormones, especially testosterone.’’
 In the presence of the SRY gene on the Y chromosome (which males inherit),
Wolffian duct develops into structures such as the epididymis, vas deferens, and seminal vesicles.
 The hormones produced by the testes, including testosterone and anti-Müllerian hormone (AMH), stimulate the
development of the Wolffian duct into these male reproductive structures.
2.Müllerian Duct:
The Müllerian duct is another embryonic structure with the potential to develop into female reproductive organs.
 In the absence of the SRY gene (which females inherit), the Müllerian duct develops into structures like the
fallopian tubes, uterus, and part of the vagina.
 Lack of testosterone and AMH allows the Müllerian duct to progress along the female developmental pathway
(Sadler TW. Langman's Medical Embryology. 13th edition. Philadelphia: Wolters Kluwer; 2014.)

7. Fig 1.2 Wolfian duct and mullerian
https://www.ncbi.nlm.nih.gov/books/NBK27042/figure/uterinestemcells.F2/
 In summary, the Wolffian and Müllerian
ducts represent two parallel
developmental pathways in embryonic
development, poised to become male or
female reproductive structures, depending
on the hormonal and genetic cues present.
 The interplay of these ducts and
associated hormones is crucial in the
complex process of gender differentiation
during fetal development.

8. SRY Gene : The male determining factor
❑Located on short arm form
of theY chromosome.
❑This gene causing male
gonadal development
Fig 1.3 SRY gene
https://images.app.goo.gl/dvRZD7oSN9BxsuxF9l

9. Factors impact on Gender
Selection
The timing of intercourse in relation to the
woman's menstrual cycle is believed by
some to influence the likelihood of
conceiving a boy or a girl.
Other hormones influenced:
 Estrogen and progesterone
 FSH and LH
 Testosterone
 AMH
 Human Chorionic Gonadotropin (hCG)
Hormonal Fluctuations:
 Hormonal fluctuations throughout the
menstrual cycle can affect the environment
within the reproductive system, potentially
influencing the survival and motility of sperm
with different chromosomes.
 Some studies suggest that changes in cervical
mucus and pH levels during the menstrual
cycle may play a role in sperm selection.

10. The Shettles Method
The Shettles Method, suggests that having intercoursecloserto ovulationincreasesthe chances
of conceivinga boy, as Y-chromosome-bearingsperm (which produce males)are considered
fasterswimmers.
❑Ovulation Prediction:
Relies on accurate prediction of ovulation.
Methods include ovulation prediction kits, basal body temperature tracking, and cervical mucus changes.
❑Sperm Characteristics:
Assumes differences in X (female) and Y (male) chromosome-carrying sperm.
Y-chromosome sperm believed to be faster but more fragile; X-chromosome sperm hardier but slower.
❑Limited Scientific Backing:
Not universally accepted within the scientific and medical communities.
Scientific studies have not consistently supported its effectiveness.
Whelan Method: Involves tracking basal body temperature to determine the timing of ovulation.

11. Table 1: Characteristics differences between the X and Y chromosomes of the sperm
X Chromosomes Y Chromosomes
Producesa female baby Producesa male baby
Always larger than Y Always smaller than X
Has a longer life span than Y Chromosomes Has a shorter life span than X
Chromosomes Noticed to be a long distance
swimmer with slow speed
Noticed to be a short distance swimmer with
more speed than X chromosomes
Can survive in relatively higher acidic vagina Cannot survive in high acidic vagina. Prefers an
alkaline surrounding

12. PCOS
Polycystic ovary syndrome (PCOS) is common in women, and its pathophysiology appears to be polygenic and multifactorial. It
is characterized by abnormal metabolic, endocrine, and reproductive factors, and is clinically diagnosed depending on
anovulation/oligo-ovulation, hyperandrogenism, and polycystic ovaries.
 Impact on Gender Selection: Irregular ovulation makes it challenging to predict the fertile window accurately, potentially
affecting the timing of conception and the success of gender selection methods.
According to latest research: (Yang, M., Zhang, et al 2023)
 In this retrospective cohort study, the records of 1,391 women with PCOS were analyzed.
 The cohort was divided into a low-AMH group (n = 700) and a high-AMH group (n = 691), based on an AMH cutoff value of
8.45 ng/ml.
 Müllerian duct anomalies were classified into four subtypes based on threedimensional ultrasonography: septate uterus,
bicornuate uterus, uterus didelphys, unicornuate uterus, and arcuate uterus. The primary outcome was the overall incidence of
Müllerian duct anomalies. The secondary outcome was the prevalence of the abovementioned specific types of Müllerian duct
anomalies.
This study confirmed it confirmed a higher prevalence of unicornuate uterus in PCOS women with high AMH levels. Clinicians
might decide to investigate the possibility of a unicornuate uterus in PCOS women with high AMH levels.

13. Fig 1.4 The role of AMH in PCOS
https://images.app.goo.gl/J9LEiqsTuYponxzj9

14. The persistent Müllerian duct syndrome
 Mutations inactivating AMH or its receptorAMHRII lead to the Persistent Müllerian Duct Syndrome
(PMDS) in otherwise normally virilized 46,XY males.
 . Abnormalities of male excretory ducts are frequent.
 Testicular malignant degeneration occurs in 33% of adults with the disorder.
 Cancer of Müllerian derivatives is less frequent.
 Fertility is rare but possible if at least one testis is scrotal and its excretory ducts are intact.
 Eighty families with 64 different mutations of the AMH gene have been identified, mostly in exons 1, 2 and
5. AMHRII gene mutations representing 58 different alleles have been discovered in 75 families. The most
common mutation, a 27 bp deletion in the kinase domain, was found in 30 patients of mostly Northern
European origin. In 12% of cases, no mutation of AMH or AMHRII has been detected, suggesting a
disruption of other pathways involved in Müllerian regression. (Picard, J. Y., Cate, et al 2017)

15. Fig. 1.5 The 3 main clinical presentations of PMDS. A Bilateral cryptorchidism. The testes are located in the
pelvis, in the position of normal ovaries.
https://images.app.goo.gl/8r1vMiHsgC2VewAA6
Three presentations exist:
bilateral cryptorchidism,
unilateral cryptorchidism
with contralateral hernia,
and transverse testicular
ectopia.

16.  Relationship of Vaccine and Infertility (Mohr-Sasson, A., Haas, J., Abuhasira, et al 2022)
❑ In the present study, they found that plasma AMH levels before and 3 months following two mRNA SARS-
CoV-2 vaccinations did not change significantly. This finding was consistent also after analyzing different age
groups.
❑ All vaccinated women in this study demonstrated elevated anti-Covid-19 antibody levels at 3 months.
❑ They did not find any association between antibody levels and AMH levels.
 AMH and interaction with placental biomarkers in early pregnancy ( T I M, K., Kumar, A., Kalra, B., et al 2023)
❑ In this large study, we show that AMH levels in early pregnancy decrease with advancing gestational age.
❑ The association betweenAMH and the placental biomarkers hCG, sFLT, and PLGF suggests a better placental
development with lower vascular resistance in mothers with higher AMH levels.
✓ Hence, AMH might be useful in predicting adverse pregnancy outcomes due to impaired placental
development

17. Gender Selection and IVF
There are different methods for gender selection, and they vary in terms of their reliability and ethical
considerations.
1. Preimplantation Genetic Diagnosis (PGD): This method involves in vitro fertilization (IVF), where embryos are
created outside the body. Before implantation, a single cell is removed from each embryo, and its sex is determined.
Only embryos of the desired sex are then implanted in the uterus. PGD is a highly effective method but is often
associated with ethical concerns.
2. Sperm Sorting: This method separates sperm into X and Y chromosomes based on their weight. Couples can then
choose which sperm to use for conception. While it's less invasive than PGD, its success rates may vary.
3. Ericsson Method:This technique involves separating sperm based on their swimming speed. The idea is that X-
chromosome-bearing sperm (female) swim slower than Y-chromosome-bearing sperm (male). However, its
reliability is debated.
4. Natural Methods: Timing intercourse based on the woman's menstrual cycle is a less invasive method. The theory
is that different timing favors the conception of male or female embryos. However, this method is less reliable
compared to others.

19.  Halim, N. R. B., Elmahaishi, H., & Elmahaishi, M. S. (2023). Does gender selection works? An observational study. Archives of
Clinical Trials, 1-8
 Jimoh, R. G., Fadairo, O. S., & Abdulsalam, S. O. A SHETTLE’S METHOD MODEL FOR AUTOMATING PRECONCEPTION
SEX SELECTION.
 Yang, M., Zhang, F., Wu, K., Yu, D., Zhang, Y., Liao, Y., ... & Wang, Y. (2023). Müllerian Duct Anomalies and Anti-Müllerian
Hormone Levels in Women With Polycystic Ovary Syndrome. Cureus, 15(8).
 Mohr-Sasson, A., Haas, J., Abuhasira, S., Sivan, M., Doitch Amdurski, H., Dadon, T., ... & Rabinovici, J. (2022). The effect of
Covid-19 mRNA vaccine on serum anti-Müllerian hormone levels. Human Reproduction,37(3), 534-541.
 T I M, K., Kumar, A., Kalra, B., Savjani, G. V
., Steegers, E. A. P., Louwers, Y. V
., & Laven, J. S. E. (2023). Reference ranges of
anti‐Müllerian hormone and interaction with placental biomarkers in early pregnancy: the Generation R Study, a population-based
prospective cohort study. Endocrine, 12, e220320.
 Picard, J. Y., Cate, R. L., Racine, C., & Josso, N. (2017). The persistent Müllerian duct syndrome: an update based upon a personal
experience of 157 cases. Sexual Development, 11(3), 109-125.
References