Harderian glands, first described by Jacob Harder in two species of deer in 1694, are large, intraorbital glands which, with but few exceptions, are found in all land vertebrates. Certainly, their relatively large size, their phylogenetic age, and persistent conservation in all groups as they emerged from an aqueous to an air/land environment lend strong support to the logical deduction that they probably play an important role in the physiological adaptation to terrestrial life. Yet, few biologists know even what or where these glands are. For a variety of reasons, the Harderian glands have not received the attention they deserve and, as a result, the published works available have been scarce and scattered throughout the world literature. The current situation is remarkably similar to that which existed in regard to the pineal gland prior to the mid-1960s, i. e. , scattered literature, unknown function, few investigators, and little interest. Yet, following a few key papers, interest in the pineal gland expanded and soon an explosive increase in the knowledge and understanding of the pineal gland took place and continues today. Will history repeat itself? Originally, a few of us discussed the desirability of an informal Symposium on the Harderian glands.

The Past, Present and Future of the Harderian Gland

Comparative Anatomy of the Mammalian Harderian Glands
1 Introduction
2 Harderian Gland in Individual Mammalian Species
3 Macroscopic Anatomy of the Mammalian Harderian Gland
3.1 Location and Shape of the Harderian Gland
3.2 Duct of the Harderian Gland
3.3 Innervation
3.4 Orbital Venous Sinus
4 Comparative Anatomy of the Harderian Gland
4.1 Mammalian Harderian Gland
4.2 Harderian Gland in Mammals and Lower Vertebrates
References
Harderian Glands and Their Development in Laboratory Rats and Mice
1 Introduction
2 Histological Organization
2.1 Secretory Epithelium
2.2 Myoepithelial Cells
2.3 Interstitial Connective Tissue
2.4 Cytology
3 Secretory Products
3.1 Lipids
3.2 Porphyrins
3.3 Melatonin
3.4 Other products
4 Innervations
5 Development
6 Hormones
6.1 Gonadal Steroids
6.2 Thyroid Hormones
7 Light
8 Tumours and Diseases
9 Ocular Immune System
10 Conclusions
References
The Structure of the Harderian Gland of the Golden Hamster
1 Introduction
2 General Features
3 Particular Features
3.1 The Epithelial Cells
3.1.1 The Epithelial Cells of the Male Gland
3.1.2 The Epithelial Cells of the Female Gland
3.1.3 Classification of Epithelial Cell Types
3.2 The Luminal Contents
3.3 Myoepithelial Cells
3.4 Interstitial Tissues
3.5 The Secretory Duct
4 Hormones and the Harderian Gland
5 Development of the Hamster Harderian Gland
6 Comparisons with Other Species and Overview
References
The Mammalian Harderian Gland: Ultrastructure, Sexual Dimorphism, and Its Regulation by Light and Steroids
1 Introduction
2 Secretory Epithelium
2.1 Rabbit
2.2 Armadillo
2.3 Gerbil
2.4 Rat
2.5 Mouse
2.6 Plains Mouse
2.7 Woodmouse
2.8Hamster
3 Secretory Products
3.1 Lipids
3.2 Porphyrin
4 Myoepithelial Cells
5 Innervation
6 Secretory Duct
7 Sexual Dimorphism
7.1 Influence of Light
7.2 Regulation by Steroids
References
The Harderian Gland of Amphibians and Reptiles
1 Introduction
2 Embryology
2.1 Amphibians
2.2 Reptiles
3 Gross Anatomy
3.1 Amphibians
3.2 Reptiles
4 Histology and Ultrastructure
4.1 Amphibians
4.2 Reptiles
5 Histochemistry
5.1 Amphibians
5.2 Reptiles
6 Regulation of the Secretory Activity
6.1 Exogenous Factors
6.2 Endogenous Factors
7 Pinealectomy
8 Hypophysectomy
9 Sex Hormones
10 Putative Functions
11 Concluding Remarks
References
Morphology of the Harderian Gland in the Rabbit. A Short Review
1 Introduction
2 Gross Anatomy
3 Morphology
3.1 Light Microscopy
3.2 Electron Microscopy
3.3 Innervation
3.4 Lipid Droplet Section
4 Histochemistry-Biochemistry
5 Conclusions
References
The Function of the Harderian Gland in the Mongolian Gerbil, Meriones unguiculatus
1 Introduction
2 The Release of Harderian Gland Secretions
3 Chemical Communication and Harderian Gland Function
4 Thermoregulation and Osmoregulation
5 The Delicate Balance
References
Gonadal Hormones, Structure and Porphyrin Synthesis in the Rodent Harderian Gland
1 Sex Differences in Porphyrin Synthesis and Gland Structure
2 Hormone Changes, Gland Structure and Porphyrin Synthesis
2.1 The Male Hamster Harderian Gland
2.2 The Female Hamster Harderian Gland
2.3 Interrelation Between Structure and Porphyrin Synthesis
2.4 Why Should Hormones Affect the Harderian Gland?
2.4.1 Because it is a gland of ectodermal origin
2.4.2 Because it synthesises porphyrins
2.4.3 Because it is a site of immune response
2.4.4 Because it synthesises lipids
2.4.5 Because it produces pheromones
2.5 How Can We Use This Interrelationship?
References
The Harderian Gland in Birds: Histology and Immunology
1 Introduction
2 The Shape of the Avian Harderian Glands
3 Secretory Duct
4 Histology
5 Secretory Mechanism
6 Secretory Products
7 Plasma Cell and Lymphocytes
8 Immune Status of the Fowl Harderian Gland
9 Immunoglobulin Production
10 Specific Antibody Production
References
Porphyrins and Their Possible Significance in Harderian Glands
1 Introduction
2 Haem Biosynthesis
2.1 ALA Synthase (EC 2.3.1.37)
2.2 ALA Dehydratase (EC 4.2.1.24)
2.3 PBG Deaminase (EC 4.3.1.8) and Uroporphyrinogen 3-Cosynthase (EC 4.2.1.75)
2.4 Uroporphyrinogen Decarboxylase (EC 4.1.1.37)
2.5 Coproporphyrinogen Oxidase (EC 1.3.3.3)
2.6 Protoporphyrinogen Oxidase (EC 1.3.3.4)
2.7 Ferrochelatase (EC 4.99.1.1)
3 Control of Haem Biosynthesis
3.1 The Role of ALA Synthase
3.2 Glycine
3.3 Control in Normal Subjects and in Porphyrins
3.4 Measurement of Porphyrins and their Enzymes
4 Porphyria
5 Porphyrin Synthesis in the Rodent Harderian Gland
6 Histological Appearance of Porphyrins in the Harderian Gland
6.1 Histological Preparation
6.2 Effects of Drugs
7 Factors Influencing Porphyrin Synthesis in the Harderian Gland
7.1 Species Differences
7.2 Age and Strain
7.3 Sex Differences
7.4 Effects of Temperature and Lighting
8 Harderianectomy and Porphyrin Synthesis
9 Porphyrins and Cancer Susceptibility
10 The Possible Significance of Harderian Gland Porphyrins
10.1 Lubrication
10.2 Pheromones and Thermoregulation
10.3 Phototransduction
10.4 Reproductive Function
References
Lipids in Harderian Glands and Their Significance
1 Introduction
2 Chemical Diversity of Lipids
2.1 Secretory Lipids
2.1.1 Rabbit
2.1.2 Guinea Pig
2.1.3 Rat
2.1.4 Mouse
2.1.5 Mouse Tumour
2.1.6 Golden Hamster
2.1.7 Mongolian Gerbil
2.2 Nonsecretory Neutral Lipids
2.2.1 Rabbit
2.2.2 Guinea Pig
2.2.3 Rat
2.2.4 Mouse
2.2.5 Mouse Tumour
2.2.6 Golden Hamster
2.2.7 Mongolian Gerbil
2.3 Phospholipids
2.3.1 Rabbit
2.3.2 Guinea Pig
2.3.3 Rat
2.3.4 Mouse
2.3.5 Golden Hamster
2.4 Glycolipids
2.4.1 Guinea Pig
2.4.2 Rat and Mouse
3 Enzymes Related to Lipid Synthesis
3.1 Fatty Acid Synthase
3.2 Enzymes in the Ether-Lipid Synthesis
3.2.1 Dihydroxyacetone Phosphate Acyltransferase
3.2.2 Alkyl-DHAP Synthase
3.2.3 Alkylacylglycerol Acyltransferase
3.2.4 Alkylglycerol Phosphotransferase
3.2.5 Alkylglycerol-3-Phosphate Acyltransferase
4 Significance of Lipids in the Harderian Gland
References
Harderian Gland Indoles
1 Introduction
2 Indole Synthesis and Metabolism
3 Indoles in the Rodent Harderian Gland
3.1 Melatonin
3.2 Other Indoles
4 Indoles in the Harderian Glands of Nonrodent Species
5 Are Harderian Gland Indoles Secreted to Circulation?
6 Conclusions
References
Harderian Gland Peptides
1 Introduction
2 Somatostatin
3 Vasoactive Intestinal Polypeptide (VIP)
4 Substance P
5 Arginine Vasopressin and Oxytocin
6 Neurotensin (NT), Cholecystokinin (CCK), Neuropeptide Y (NPY) and Calcitonin-Gene-Related-Peptide (CGRP)
7 Harderian Gland-Derived Growth Factor (HGDGF)
8 Thyrotropin-Releasing Hormone (TRH)
9 Summary
References
Adrenergic Activity in the Male Rat Harderian Gland
1 Introduction
2 Experimental Procedures
2.1 Animals
2.2 Tyrosine Hydroxylase Activity
2.3 Catecholamine Concentration
2.4 Chromatographic Conditions
2.5 Hormonal Determination
2.6 Statistical Analysis
3 Experimental Findings
4 Commentary and Conclusions
References
The Interrelationship Between the Harderian Glands and the Neuroendocrine-Thyroid Axis in Rodents
1 Introduction
2 Graves Ophthalmopathy and the Harderian Gland
3 Effects of the Neuroendocrine-Thyroid Axis on Harderian Glands
3.1 Weights, Morphology, Composition
3.2 Porphyrins
3.3 Indoles
4 Response of Harderian Glands to Thyrotropin and Thyroid Hormones
5 Effects of Harderian Glands on Thyroid Hormones
6 Conclusions
References
Type II 5?-Deiodinase in the Harderian Gland
1 Introduction
2 Characteristics of the Type II 5?-Deiodinase Enzyme
3 Photoperiod and Type II 5?-Deiodinase Activity
References
The Pineal and the Harderian Glands: Evidence for Mutual Interactions
1 Introduction
2 Evidence for Harderian Gland Effects on the Pineal Gland
3 Evidence for Pineal Gland Effects on the Harderian Glands
4 Final Comment
References
The Harderian Gland as a Target for Steroid Hormone Action: Role and Characteristics of Intracellular Receptors
1 Introduction
2 Genomic Mechanisms of Steroid Hormone Action
3 Androgen Receptors
4 Progesterone Receptors
5 Estrogen Receptors
6 Other Hormone Receptors
7 Concluding Remarks
References
Additional References.