ABP	androgen-binding protein
AKT	protein kinase B
ARTs	assisted reproductive technologies
BDNF	brain-derived neurotrophic factor
CAVD	congenital absence of the vas deferens
CML	chronic myeloid leukemia
CREB	c-AMP-response element binding protein
DAG	diacylglycerol
EdU	5-ethynyl-2′-deoxyuridine
ERK	extracellular signal-regulated kinase
FSH	follicle-stimulating hormone
GnRH	gonadotropin-releasing hormone
GRB2	growth factor receptor-bound protein 2
HH	hypogonadotropic hypogonadism
HPG	hypothalamus–pituitary–gonadal
ICSI	intracytoplasmic sperm injection
ILCs	immature Leydig cells
IP3	inositol triphosphate
IUI	intrauterine insemination
IVF	in vitro fertilization
LC	Leydig cell
LH	luteinizing hormone
MAPK	mitogen-activated protein kinase
MEK	mitogen-activated protein kinase
NGF	nerve growth factor
NO	nitric oxide
NT-3	neurotrophin-3
NT-4	neurotrophin-4
OA	obstructive azoospermia
PADAM	partial androgen deficiency of the aging male
PDK	3-phosphoinositide-dependent kinase 1
PI3K	phosphoinositide 3-kinase
PIP2	phosphatidylinositol 4,5-bisphosphate
PIP3	phosphatidylinositol 3,4,5-trisphosphate
PKC	protein kinase C
PLC-γ	phosphoinositide-specific phospholipase C-γ
PLCs	progenitor Leydig cells
PM	progressive motility
RAF	rapidly accelerated fibrosarcoma
ROS	reactive oxygen species
SC	Sertoli cell
SERMs	selective estrogen receptor modulators
SHC	src honology and collagen
SLCs	stem Leydig cells
TST	testosterone supplementation therapy
WHO	World Health Organization