Скачать или смотреть Development of Hair & Sebaceous Glands | Embryology | 3D Animation

Hello! I'm Dr. Aizaz from MedicoVisual, and welcome to a new visual lecture from our "Premium 3D Integumentary System Embryology MasterClass." In this detailed 3D animated video, we will explore the fascinating embryological development of hair, sebaceous glands, and the arrector pili muscle.

Join me as we journey deep into the microscopic world of the developing skin to understand how these complex structures form, layer by layer. Using highly detailed 3D models, we will make these intricate concepts crystal clear, ensuring you build a strong and lasting understanding.

INTRODUCTION
We begin with the two-layered stage of the skin and witness the very first step in hair development.

HAIR PEG & HAIR BULB FORMATION
Watch as the stratum basale extends downwards into the dermis, forming a structure called the hair peg. We'll see how its lower end dilates to become the hair bulb, the foundation of the future hair follicle.

THE DERMAL HAIR PAPILLA
In a fun twist, see how the dermis "takes revenge" by invaginating into the base of the hair bulb. This crucial structure, the dermal hair papilla, brings in blood vessels to nourish the developing hair.

THE HAIR BULGE: A STEM CELL NICHE
Discover the "hair bulge," a critical region of undifferentiated stem cells that forms between the future attachment point of the arrector pili muscle and the opening of the sebaceous gland.

HAIR MATRIX: THE BIRTHPLACE OF HAIR
Follow the migration of stem cells from the hair bulge down to the base, forming the hair matrix. This is the powerhouse of proliferation for the hair shaft and its sheaths. We'll also see how neural crest cells migrate in to become melanocytes, providing the hair with its pigment.

HISTOLOGY OF THE HAIR AND FOLLICLE
We'll take a detailed cross-section to reveal the layers of the hair and its follicle:
• Hair Shaft: Composed of the Medulla, Cortex, and the outer Cuticle.
• Internal Root Sheath: A multi-layered sheath that extends up to the sebaceous gland.
• External Root Sheath: A direct continuation of the epidermis's stratum basale.
• Epithelial & Fibrous Sheaths: Understand how the internal and external sheaths form the epithelial root sheath, and how it's encased by a connective tissue-based fibrous (or dermal) sheath.

KERATINIZATION VS. CORNIFICATION
A very important concept! I'll clarify the difference between keratinization (filling with keratin) and cornification (a specialized programmed cell death where the nucleus is lost). This explains why the base of the hair is alive, but the shaft we see is not, and why you don't feel pain during a haircut. We'll also pinpoint "Adamson's fringe," the line where this process begins.

DEVELOPMENT OF THE SEBACEOUS GLAND
See how another outgrowth from the hair follicle wall develops into a simple branched acinar gland—the sebaceous gland, responsible for secreting oily sebum.

DEVELOPMENT OF THE ARRECTOR PILI MUSCLE
Watch as mesenchymal cells organize to form this tiny smooth muscle. We'll demonstrate how its contraction causes the hair to stand on end, leading to "goosebumps" (piloerection).

LANUGO HAIR
Finally, we'll discuss Lanugo hair—the fine, less pigmented hair found on a fetus, which is typically shed around birth and replaced by coarser, more mature hair.