Human Development Lecture Notes PDF

2/7/2025 HUMAN DEVELOPMENT CAROLINA MENDOZA, MD COM 5081- FUNDAMENTALS OF PATHOLOGY 1 1 Lecture Objectives 1. Identify the stages in normal development of the human embryo 2. Recognize...

2/7/2025 HUMAN DEVELOPMENT CAROLINA MENDOZA, MD COM 5081- FUNDAMENTALS OF PATHOLOGY 1 1 Lecture Objectives 1. Identify the stages in normal development of the human embryo 2. Recognize the abnormalities associated with human embryonic development 3. Identify teratogens associated with human embryogenesis 4. Identify congenital anomalies associated with various stages of embryogenesis 2 2 3 3 1  2/7/2025 STAGES OF HUMAN DEVELOPMENT 1. FERTILIZATION 2. BLASTOCYST DEVELOPMENT AND IMPLANTATION 3. EMBRYOLOGIC DEVELOPMENT 4. FETAL DEVELOPMENT 4 4 FERTILIZATION 5 5 DAY 0 FERTILIZATION Sperm and ova are called gametes Each has 23 chromosomes Father provides the sex determining chromosome 6 6 2  2/7/2025 WHAT CAN GO WRONG? Polycystic Ovarian Syndrome (PCOS)/ Insulin resistance How? Fallopian tube stricture secondary to salpingitis Which bugs? Sperm dysmotility What genetic condition? 7 7 BLASTOCYST DEVELOPMENT AND IMPLANTATION 8 8 ~DAY 6 IMPLANTATION Fast cell division Zygote  Morula  Blastocyst Blastocyst sticks on Implantation occurs between day 6 and 10 day six HCG secretion starts around that time 9 9 3  2/7/2025 WHAT CAN GO WRONG? 10 10 EARLY EMBRYOLOGIC EMBRYO- WEEKS 2 TO 8 DEVELOPMENT 11 11 WEEKS 2 to 8 EMBRYO DEVELOPMENT By week 3, there are 3 primary germ layers 12 12 4  2/7/2025 13 13 WHAT CAN GO WRONG? Neural tube ? Upper and lower extremities? Heart? 14 14 15 15 5  2/7/2025 FETAL DEVELOPMENT 16 16 WEEKS 9 TO 38 FETAL DEVELOPMENT Criteria for gestational viability: Age in weeks? Weight in grams? 17 17 WHAT CAN GO WRONG? This period is less sensitive for major congenital anomalies when compared to the fetal stage It is, however, very critical for functional defects 18 18 6  2/7/2025 TERATOGENS ANY AGENT THAT CAUSES AN ABNORMALITY FOLLOWING FETAL EXPOSURE 19 19 TERATOGENS Usually discovered after an increased prevalence of a particular birth defect -Infectious agents -Medications and recreational drugs -Physical agents (ionizing radiation, hyperthermia) -Maternal health factors (diabetes, maternal PKU, nutritional deficiencies such as folate) -Environmental chemicals (organic mercury compounds, polychlorinated biphenyl or PCB, herbicides and industrial solvents) 20 20 INFECTIOUS TORCH T: Toxoplasma gondii O: Others HIV, Hepatitis, Syphilis, Varicella-Zoster, Parvovirus R: Rubella C: Cytomegalovirus H: Herpes simplex virus EMBRYOLOGIC STATE growth restriction, mental retardation, cataracts, and congenital cardiac anomalies FETAL STAGE- result primarily in tissue injury accompanied by inflammation (encephalitis, chorioretinitis, hepatosplenomegaly, pneumonia, and myocarditis). 21 21 7  2/7/2025 COMMON SYMPTOMS hepatosplenomegaly fever poor feeding growth retardation jaundice thrombocytopenia hearing impairment Developmental delay autism death 22 22 SUBSTANCES- LEGAL AND ILLEGAL Neural tube defects with Retinoic acid 23 23 CONGENITAL ANOMALIES 24 24 8  2/7/2025 ERRORS IN MORPHOGENESIS 25 25 Malformations - primary errors of morphogenesis: result from intrinsically abnormal development; multifactorial in origin; range in severity from the incidental to the lethal e.g. cleft lip/palate Disruptions - result from secondary destruction of an organ or body region that was previously normal in development; arise from an extrinsic disturbance in morphogenesis from a variety of environmental agents e.g. amniotic bands 26 26 Deformations - also represent an extrinsic disturbance of development rather than an intrinsic error of morphogenesis; caused by localized or generalized compression of the growing fetus by abnormal biomechanical forces. e.g. congenital arthrogryposis Sequence - One or more secondary morphologic anomalies known or presumed to cascade from a single malformation, disruption, dysplasia, or deformation e.g. Potter sequence Syndrome - Recognizable pattern of congenital anomalies that are known or thought to be causally related e.g. Fetal alcohol syndrome 27 27 9  2/7/2025 POTTER SEQUENCE OLIGOHYDRAMNIOS  FETAL GROWTH RESTRICTION  ORGAN HYPOPLASIA   28 28 NEURAL TUBE DEFECTS 29 29 NEURAL TUBE DEFECTS (cranial end) Encephalocele Anencephaly Birth defect where a Severe birth defect portion of the brain where the cranial part protrudes through a of the neural tube fails gap in the skull to close during fetal development, resulting in the absence of significant portions of the brain, skull, and scalp 30 30 10  2/7/2025 NEURAL TUBE DEFECTS (caudal end) Include Spina bifida,, Encephalocele - Spina bifida is the most common NTD failure of complete closure of the neural tube Associated with folate deficiency Adjust Rxs and supplement! Sacral dimple or tuft of hair 31 31 CITED SOURCES https://www.sciencedirect.com/science/article/pii/S0012160620303195#tbl2 https://www.ihrfertility.com/blog/top-pcos-fertility-facts https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4819317/#:~:text=CF%20affects%20reproducti ve%20health%20by,%2C%20epididymis%2C%20and%20seminal%20vesicles. Germ layer derivatives (video) | Embryology | Khan Academy Critical Periods of Development - Mother To Baby | Fact Sheets - NCBI Bookshelf (nih.gov) https://www.ncbi.nlm.nih.gov/books/NBK132176 FIRST AID for the USMLE Step 1. 2023 https://mhebooklibrary- com.ezproxylocal.library.nova.edu/ 32 32 11